diff --git a/app/assets/javascripts/admin/addon/components/admin-flags.gjs b/app/assets/javascripts/admin/addon/components/admin-config-areas/flags.gjs
similarity index 63%
rename from app/assets/javascripts/admin/addon/components/admin-flags.gjs
rename to app/assets/javascripts/admin/addon/components/admin-config-areas/flags.gjs
index b6f5c130d93..3be32a52704 100644
--- a/app/assets/javascripts/admin/addon/components/admin-flags.gjs
+++ b/app/assets/javascripts/admin/addon/components/admin-config-areas/flags.gjs
@@ -6,9 +6,10 @@ import { ajax } from "discourse/lib/ajax";
 import { popupAjaxError } from "discourse/lib/ajax-error";
 import i18n from "discourse-common/helpers/i18n";
 import { bind } from "discourse-common/utils/decorators";
+import AdminConfigHeader from "admin/components/admin-config-header";
 import AdminFlagItem from "admin/components/admin-flag-item";
 
-export default class AdminFlags extends Component {
+export default class AdminConfigAreasFlags extends Component {
   @service site;
   @tracked flags = this.site.flagTypes;
 
@@ -46,19 +47,39 @@ export default class AdminFlags extends Component {
     });
   }
 
+  @action
+  deleteFlagCallback(flag) {
+    return ajax(`/admin/config/flags/${flag.id}`, {
+      type: "DELETE",
+    })
+      .then(() => {
+        this.flags.removeObject(flag);
+      })
+      .catch((error) => popupAjaxError(error));
+  }
+
   <template>
     <div class="container admin-flags">
-      <h1>{{i18n "admin.flags.title"}}</h1>
-      <table class="flags grid">
+      <AdminConfigHeader
+        @name="flags"
+        @heading="admin.config_areas.flags.header"
+        @subheading="admin.config_areas.flags.subheader"
+        @primaryActionRoute="adminConfig.flags.new"
+        @primaryActionCssClass="admin-flags__header-add-flag"
+        @primaryActionIcon="plus"
+        @primaryActionLabel="admin.config_areas.flags.add"
+      />
+      <table class="admin-flags__items grid">
         <thead>
-          <th>{{i18n "admin.flags.description"}}</th>
-          <th>{{i18n "admin.flags.enabled"}}</th>
+          <th>{{i18n "admin.config_areas.flags.description"}}</th>
+          <th>{{i18n "admin.config_areas.flags.enabled"}}</th>
         </thead>
         <tbody>
           {{#each this.flags as |flag|}}
             <AdminFlagItem
               @flag={{flag}}
               @moveFlagCallback={{this.moveFlagCallback}}
+              @deleteFlagCallback={{this.deleteFlagCallback}}
               @isFirstFlag={{this.isFirstFlag flag}}
               @isLastFlag={{this.isLastFlag flag}}
             />
diff --git a/app/assets/javascripts/admin/addon/components/admin-config-header.gjs b/app/assets/javascripts/admin/addon/components/admin-config-header.gjs
new file mode 100644
index 00000000000..458789349ca
--- /dev/null
+++ b/app/assets/javascripts/admin/addon/components/admin-config-header.gjs
@@ -0,0 +1,34 @@
+import Component from "@glimmer/component";
+import { LinkTo } from "@ember/routing";
+import concatClass from "discourse/helpers/concat-class";
+import dIcon from "discourse-common/helpers/d-icon";
+import i18n from "discourse-common/helpers/i18n";
+
+export default class AdminFlagItem extends Component {
+  get headerCssClass() {
+    return `admin-${this.args.name}__header`;
+  }
+  <template>
+    <div class={{this.headerCssClass}}>
+      <h2>{{i18n @heading}}</h2>
+      {{#if @primaryActionRoute}}
+        <LinkTo
+          @route={{@primaryActionRoute}}
+          class={{concatClass
+            "btn-primary"
+            "btn"
+            "btn-icon-text"
+            @primaryActionCssClass
+          }}
+        >
+          {{dIcon @primaryActionIcon}}
+          {{i18n @primaryActionLabel}}
+        </LinkTo>
+      {{/if}}
+
+      {{#if @subheading}}
+        <h3>{{i18n @subheading}}</h3>
+      {{/if}}
+    </div>
+  </template>
+}
diff --git a/app/assets/javascripts/admin/addon/components/admin-flag-item.gjs b/app/assets/javascripts/admin/addon/components/admin-flag-item.gjs
index 1db3093d63e..a6435d31b05 100644
--- a/app/assets/javascripts/admin/addon/components/admin-flag-item.gjs
+++ b/app/assets/javascripts/admin/addon/components/admin-flag-item.gjs
@@ -3,7 +3,9 @@ import { tracked } from "@glimmer/tracking";
 import { fn } from "@ember/helper";
 import { on } from "@ember/modifier";
 import { action } from "@ember/object";
+import { inject as service } from "@ember/service";
 import { htmlSafe } from "@ember/template";
+import { not } from "truth-helpers";
 import DButton from "discourse/components/d-button";
 import DToggleSwitch from "discourse/components/d-toggle-switch";
 import DropdownMenu from "discourse/components/dropdown-menu";
@@ -14,22 +16,48 @@ import i18n from "discourse-common/helpers/i18n";
 import DMenu from "float-kit/components/d-menu";
 
 export default class AdminFlagItem extends Component {
+  @service dialog;
+  @service router;
+
   @tracked enabled = this.args.flag.enabled;
 
   get canMove() {
     return this.args.flag.id !== SYSTEM_FLAG_IDS.notify_user;
   }
 
+  get canEdit() {
+    return (
+      !Object.values(SYSTEM_FLAG_IDS).includes(this.args.flag.id) &&
+      !this.args.flag.is_used
+    );
+  }
+
+  get editTitle() {
+    return this.canEdit
+      ? "admin.config_areas.flags.form.edit_flag"
+      : "admin.config_areas.flags.form.non_editable";
+  }
+
+  get deleteTitle() {
+    return this.canEdit
+      ? "admin.config_areas.flags.form.edit_flag"
+      : "admin.config_areas.flags.form.non_editable";
+  }
+
   @action
   toggleFlagEnabled(flag) {
     this.enabled = !this.enabled;
 
     return ajax(`/admin/config/flags/${flag.id}/toggle`, {
       type: "PUT",
-    }).catch((error) => {
-      this.enabled = !this.enabled;
-      return popupAjaxError(error);
-    });
+    })
+      .then(() => {
+        this.args.flag.enabled = this.enabled;
+      })
+      .catch((error) => {
+        this.enabled = !this.enabled;
+        return popupAjaxError(error);
+      });
   }
 
   @action
@@ -48,6 +76,23 @@ export default class AdminFlagItem extends Component {
     this.args.moveFlagCallback(this.args.flag, "down");
     this.dMenu.close();
   }
+  @action
+  edit() {
+    this.router.transitionTo("adminConfig.flags.edit", this.args.flag);
+  }
+
+  @action
+  delete() {
+    this.dialog.yesNoConfirm({
+      message: i18n("admin.config_areas.flags.delete_confirm", {
+        name: this.args.flag.name,
+      }),
+      didConfirm: () => {
+        this.args.deleteFlagCallback(this.args.flag);
+      },
+    });
+    this.dMenu.close();
+  }
 
   <template>
     <tr class="admin-flag-item {{@flag.name_key}}">
@@ -64,10 +109,19 @@ export default class AdminFlagItem extends Component {
             class="admin-flag-item__toggle {{@flag.name_key}}"
             {{on "click" (fn this.toggleFlagEnabled @flag)}}
           />
+
+          <DButton
+            class="btn btn-secondary admin-flag-item__edit"
+            @action={{this.edit}}
+            @label="admin.config_areas.flags.edit"
+            @disabled={{not this.canEdit}}
+            @title={{this.editTitle}}
+          />
+
           {{#if this.canMove}}
             <DMenu
               @identifier="flag-menu"
-              @title={{i18n "admin.flags.more_options.title"}}
+              @title={{i18n "admin.config_areas.flags.more_options.title"}}
               @icon="ellipsis-v"
               @onRegisterApi={{this.onRegisterApi}}
             >
@@ -76,9 +130,9 @@ export default class AdminFlagItem extends Component {
                   {{#unless @isFirstFlag}}
                     <dropdown.item>
                       <DButton
-                        @label="admin.flags.more_options.move_up"
+                        @label="admin.config_areas.flags.more_options.move_up"
                         @icon="arrow-up"
-                        @class="btn-transparent move-up"
+                        @class="btn-transparent admin-flag-item__move-up"
                         @action={{this.moveUp}}
                       />
                     </dropdown.item>
@@ -86,13 +140,24 @@ export default class AdminFlagItem extends Component {
                   {{#unless @isLastFlag}}
                     <dropdown.item>
                       <DButton
-                        @label="admin.flags.more_options.move_down"
+                        @label="admin.config_areas.flags.more_options.move_down"
                         @icon="arrow-down"
-                        @class="btn-transparent move-down"
+                        @class="btn-transparent admin-flag-item__move-down"
                         @action={{this.moveDown}}
                       />
                     </dropdown.item>
                   {{/unless}}
+
+                  <dropdown.item>
+                    <DButton
+                      @label="admin.config_areas.flags.delete"
+                      @icon="trash-alt"
+                      class="btn-transparent admin-flag-item__delete"
+                      @action={{this.delete}}
+                      @disabled={{not this.canEdit}}
+                      @title={{this.deleteTitle}}
+                    />
+                  </dropdown.item>
                 </DropdownMenu>
               </:content>
             </DMenu>
diff --git a/app/assets/javascripts/admin/addon/components/admin-flags-form.gjs b/app/assets/javascripts/admin/addon/components/admin-flags-form.gjs
new file mode 100644
index 00000000000..07ffb00a611
--- /dev/null
+++ b/app/assets/javascripts/admin/addon/components/admin-flags-form.gjs
@@ -0,0 +1,190 @@
+import Component from "@glimmer/component";
+import { tracked } from "@glimmer/tracking";
+import { Input } from "@ember/component";
+import { hash } from "@ember/helper";
+import { TextArea } from "@ember/legacy-built-in-components";
+import { action } from "@ember/object";
+import { LinkTo } from "@ember/routing";
+import { service } from "@ember/service";
+import { isEmpty } from "@ember/utils";
+import { not } from "truth-helpers";
+import DButton from "discourse/components/d-button";
+import { ajax } from "discourse/lib/ajax";
+import { popupAjaxError } from "discourse/lib/ajax-error";
+import dIcon from "discourse-common/helpers/d-icon";
+import i18n from "discourse-common/helpers/i18n";
+import { bind } from "discourse-common/utils/decorators";
+import I18n from "discourse-i18n";
+import AdminConfigAreaCard from "admin/components/admin-config-area-card";
+import MultiSelect from "select-kit/components/multi-select";
+
+export default class AdminFlagsForm extends Component {
+  @service router;
+  @service site;
+
+  @tracked enabled = true;
+  @tracked name;
+  @tracked description;
+  @tracked appliesTo;
+
+  constructor() {
+    super(...arguments);
+    if (this.isUpdate) {
+      this.name = this.args.flag.name;
+      this.description = this.args.flag.description;
+      this.appliesTo = this.args.flag.applies_to;
+      this.enabled = this.args.flag.enabled;
+    }
+  }
+
+  get isUpdate() {
+    return this.args.flag;
+  }
+
+  get isValid() {
+    return (
+      !isEmpty(this.name) &&
+      !isEmpty(this.description) &&
+      !isEmpty(this.appliesTo)
+    );
+  }
+
+  get header() {
+    return this.isUpdate
+      ? "admin.config_areas.flags.form.edit_header"
+      : "admin.config_areas.flags.form.add_header";
+  }
+
+  get appliesToValues() {
+    return this.site.valid_flag_applies_to_types.map((type) => {
+      return {
+        name: I18n.t(
+          `admin.config_areas.flags.form.${type
+            .toLowerCase()
+            .replace("::", "_")}`
+        ),
+        id: type,
+      };
+    });
+  }
+
+  @action
+  save() {
+    this.isUpdate ? this.update() : this.create();
+  }
+
+  @bind
+  create() {
+    return ajax(`/admin/config/flags`, {
+      type: "POST",
+      data: this.#formData,
+    })
+      .then((response) => {
+        this.site.flagTypes.push(response.flag);
+        this.router.transitionTo("adminConfig.flags");
+      })
+      .catch((error) => {
+        return popupAjaxError(error);
+      });
+  }
+
+  @bind
+  update() {
+    return ajax(`/admin/config/flags/${this.args.flag.id}`, {
+      type: "PUT",
+      data: this.#formData,
+    })
+      .then((response) => {
+        this.args.flag.name = response.flag.name;
+        this.args.flag.description = response.flag.description;
+        this.args.flag.applies_to = response.flag.applies_to;
+        this.args.flag.enabled = response.flag.enabled;
+        this.router.transitionTo("adminConfig.flags");
+      })
+      .catch((error) => {
+        return popupAjaxError(error);
+      });
+  }
+
+  @bind
+  get #formData() {
+    return {
+      name: this.name,
+      description: this.description,
+      applies_to: this.appliesTo,
+      enabled: this.enabled,
+    };
+  }
+
+  <template>
+    <div class="admin-config-area">
+      <h2>{{i18n "admin.config_areas.flags.header"}}</h2>
+      <LinkTo
+        @route="adminConfig.flags"
+        class="btn-default btn btn-icon-text btn-back"
+      >
+        {{dIcon "chevron-left"}}
+        {{i18n "admin.config_areas.flags.back"}}
+      </LinkTo>
+      <div class="admin-config-area__primary-content admin-flag-form">
+        <AdminConfigAreaCard @heading={{this.header}}>
+          <div class="control-group">
+            <label for="name">
+              {{i18n "admin.config_areas.flags.form.name"}}
+            </label>
+            <Input
+              name="name"
+              @type="text"
+              @value={{this.name}}
+              maxlength="200"
+              class="admin-flag-form__name"
+            />
+          </div>
+
+          <div class="control-group">
+            <label for="description">
+              {{i18n "admin.config_areas.flags.form.description"}}
+            </label>
+            <TextArea
+              @value={{this.description}}
+              maxlength="1000"
+              class="admin-flag-form__description"
+            />
+          </div>
+
+          <div class="control-group">
+            <label for="applies-to">
+              {{i18n "admin.config_areas.flags.form.applies_to"}}
+            </label>
+            <MultiSelect
+              @value={{this.appliesTo}}
+              @content={{this.appliesToValues}}
+              @options={{hash allowAny=false}}
+              class="admin-flag-form__applies-to"
+            />
+          </div>
+
+          <div class="control-group">
+            <label class="checkbox-label admin-flag-form__enabled">
+              <Input @type="checkbox" @checked={{this.enabled}} />
+              {{i18n "admin.config_areas.flags.form.enabled"}}
+            </label>
+          </div>
+
+          <div class="alert alert-info admin_flag_form__info">
+            {{dIcon "info-circle"}}
+            {{i18n "admin.config_areas.flags.form.alert"}}
+          </div>
+
+          <DButton
+            @action={{this.save}}
+            @label="admin.config_areas.flags.form.save"
+            @ariaLabel="admin.config_areas.flags.form.save"
+            @disabled={{not this.isValid}}
+            class="btn-primary admin-flag-form__save"
+          />
+        </AdminConfigAreaCard>
+      </div>
+    </div>
+  </template>
+}
diff --git a/app/assets/javascripts/admin/addon/routes/admin-config-flags-edit.js b/app/assets/javascripts/admin/addon/routes/admin-config-flags-edit.js
new file mode 100644
index 00000000000..f8fc09a4d2f
--- /dev/null
+++ b/app/assets/javascripts/admin/addon/routes/admin-config-flags-edit.js
@@ -0,0 +1,10 @@
+import Route from "@ember/routing/route";
+import { service } from "@ember/service";
+
+export default class AdminConfigFlagsEditRoute extends Route {
+  @service site;
+
+  model(params) {
+    return this.site.flagTypes.findBy("id", parseInt(params.flag_id, 10));
+  }
+}
diff --git a/app/assets/javascripts/admin/addon/routes/admin-route-map.js b/app/assets/javascripts/admin/addon/routes/admin-route-map.js
index c53b940cb35..3c3f963604d 100644
--- a/app/assets/javascripts/admin/addon/routes/admin-route-map.js
+++ b/app/assets/javascripts/admin/addon/routes/admin-route-map.js
@@ -215,6 +215,8 @@ export default function () {
       function () {
         this.route("flags", function () {
           this.route("index", { path: "/" });
+          this.route("new");
+          this.route("edit", { path: "/:flag_id" });
         });
 
         this.route("about");
diff --git a/app/assets/javascripts/admin/addon/templates/config-flags-edit.hbs b/app/assets/javascripts/admin/addon/templates/config-flags-edit.hbs
new file mode 100644
index 00000000000..15877a741e0
--- /dev/null
+++ b/app/assets/javascripts/admin/addon/templates/config-flags-edit.hbs
@@ -0,0 +1 @@
+<AdminFlagsForm @flag={{@model}} />
\ No newline at end of file
diff --git a/app/assets/javascripts/admin/addon/templates/config-flags-index.hbs b/app/assets/javascripts/admin/addon/templates/config-flags-index.hbs
index a67eca6e56b..eb2faa393b2 100644
--- a/app/assets/javascripts/admin/addon/templates/config-flags-index.hbs
+++ b/app/assets/javascripts/admin/addon/templates/config-flags-index.hbs
@@ -1 +1 @@
-<AdminFlags />
\ No newline at end of file
+<AdminConfigAreas::Flags />
\ No newline at end of file
diff --git a/app/assets/javascripts/admin/addon/templates/config-flags-new.hbs b/app/assets/javascripts/admin/addon/templates/config-flags-new.hbs
new file mode 100644
index 00000000000..d9147e6c680
--- /dev/null
+++ b/app/assets/javascripts/admin/addon/templates/config-flags-new.hbs
@@ -0,0 +1 @@
+<AdminFlagsForm />
\ No newline at end of file
diff --git a/app/assets/javascripts/discourse/app/components/back-button.gjs b/app/assets/javascripts/discourse/app/components/back-button.gjs
index 6372b8f0ce1..6bed727f40a 100644
--- a/app/assets/javascripts/discourse/app/components/back-button.gjs
+++ b/app/assets/javascripts/discourse/app/components/back-button.gjs
@@ -1,10 +1,11 @@
 import { LinkTo } from "@ember/routing";
+import { or } from "truth-helpers";
 import dIcon from "discourse-common/helpers/d-icon";
 import i18n from "discourse-common/helpers/i18n";
 
 <template>
   <LinkTo class="btn btn-flat back-button" @route={{@route}}>
     {{dIcon "chevron-left"}}
-    {{i18n "back_button"}}
+    {{i18n (or @label "back_button")}}
   </LinkTo>
 </template>
diff --git a/app/assets/javascripts/discourse/app/lib/flag-targets/post-flag.js b/app/assets/javascripts/discourse/app/lib/flag-targets/post-flag.js
index aee12e73807..661f29b4184 100644
--- a/app/assets/javascripts/discourse/app/lib/flag-targets/post-flag.js
+++ b/app/assets/javascripts/discourse/app/lib/flag-targets/post-flag.js
@@ -20,6 +20,10 @@ export default class PostFlag extends Flag {
   flagsAvailable(flagModal) {
     let flagsAvailable = flagModal.args.model.flagModel.flagsAvailable;
 
+    flagsAvailable = flagsAvailable.filter((flag) => {
+      return flag.applies_to.includes("Post");
+    });
+
     // "message user" option should be at the top
     const notifyUserIndex = flagsAvailable.indexOf(
       flagsAvailable.filterBy("name_key", "notify_user")[0]
diff --git a/app/assets/javascripts/discourse/tests/fixtures/site-fixtures.js b/app/assets/javascripts/discourse/tests/fixtures/site-fixtures.js
index 004a9e1e4fe..b61ed7b6c22 100644
--- a/app/assets/javascripts/discourse/tests/fixtures/site-fixtures.js
+++ b/app/assets/javascripts/discourse/tests/fixtures/site-fixtures.js
@@ -590,7 +590,8 @@ export default {
           icon: null,
           id: 3,
           is_custom_flag: false,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Chat::Message"]
         },
         {
           name_key: "inappropriate",
@@ -603,7 +604,8 @@ export default {
           icon: null,
           id: 4,
           is_custom_flag: false,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Topic", "Chat::Message"]
         },
         {
           name_key: "vote",
@@ -626,7 +628,8 @@ export default {
           icon: null,
           id: 8,
           is_custom_flag: false,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Topic", "Chat::Message"]
         },
         {
           name_key: "notify_user",
@@ -639,7 +642,8 @@ export default {
           icon: null,
           id: 6,
           is_custom_flag: true,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Topic", "Chat::Message"]
         },
         {
           name_key: "notify_moderators",
@@ -651,7 +655,8 @@ export default {
           icon: null,
           id: 7,
           is_custom_flag: true,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Topic", "Chat::Message"]
         },
       ],
       topic_flag_types: [
@@ -664,7 +669,8 @@ export default {
           icon: null,
           id: 4,
           is_custom_flag: false,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Topic", "Chat::Message"]
         },
         {
           name_key: "spam",
@@ -675,7 +681,8 @@ export default {
           icon: null,
           id: 8,
           is_custom_flag: false,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Topic", "Chat::Message"]
         },
         {
           name_key: "notify_moderators",
@@ -686,7 +693,8 @@ export default {
           icon: null,
           id: 7,
           is_custom_flag: true,
-          enabled: true
+          enabled: true,
+          applies_to: ["Post", "Topic", "Chat::Message"]
         },
       ],
       archetypes: [
diff --git a/app/assets/stylesheets/common/admin/admin_config_area.scss b/app/assets/stylesheets/common/admin/admin_config_area.scss
index f5ad30b0f14..b9046069b30 100644
--- a/app/assets/stylesheets/common/admin/admin_config_area.scss
+++ b/app/assets/stylesheets/common/admin/admin_config_area.scss
@@ -1,3 +1,8 @@
+.admin-config-area {
+  .btn-back {
+    margin-bottom: 1em;
+  }
+}
 .admin-config-area-card {
   padding: 20px;
   border: 1px solid var(--primary-low);
@@ -22,4 +27,11 @@
     font-size: var(--font-down-1);
     padding: 10px 10px;
   }
+  &__control-group-horizontal {
+    display: flex;
+    margin-bottom: 18px;
+    label {
+      margin-right: 1em;
+    }
+  }
 }
diff --git a/app/assets/stylesheets/common/admin/flags.scss b/app/assets/stylesheets/common/admin/flags.scss
index 7a02e42741c..3d7f157d478 100644
--- a/app/assets/stylesheets/common/admin/flags.scss
+++ b/app/assets/stylesheets/common/admin/flags.scss
@@ -10,11 +10,67 @@
   &__options {
     display: flex;
     align-items: center;
+    justify-content: space-between;
   }
   .d-toggle-switch--label {
     margin-bottom: 0;
   }
+  .d-toggle-switch {
+    margin-right: 2em;
+  }
+  .btn-secondary {
+    padding: 0.25em 0.325em;
+    margin-right: 0.75em;
+  }
   .flag-menu-trigger {
     padding: 0.25em 0.325em;
   }
+
+  &__delete.btn,
+  &__delete.btn:hover {
+    border-top: 1px solid var(--primary-low);
+    color: var(--danger);
+    svg {
+      color: var(--danger);
+    }
+  }
+}
+
+.admin-flag-form {
+  &__enabled,
+  &__applies-to {
+    margin-bottom: 1em;
+  }
+  &__save {
+    margin-top: 1em;
+  }
+  &__info {
+    color: var(--primary-high);
+    svg {
+      color: var(--tertiary);
+    }
+  }
+  &__description {
+    width: 60%;
+  }
+  &__applies-to.select-kit.multi-select {
+    width: 60%;
+  }
+}
+
+.admin-flags__header {
+  display: flex;
+  justify-content: space-between;
+  flex-wrap: wrap;
+
+  .btn-primary {
+    align-self: center;
+  }
+
+  h3 {
+    margin-top: 1em;
+    font-size: var(--font-0);
+    font-weight: normal;
+    flex-basis: 100%;
+  }
 }
diff --git a/app/assets/stylesheets/mobile/admin_flags.scss b/app/assets/stylesheets/mobile/admin_flags.scss
index dda3b4f055f..35547808db3 100644
--- a/app/assets/stylesheets/mobile/admin_flags.scss
+++ b/app/assets/stylesheets/mobile/admin_flags.scss
@@ -1,3 +1,17 @@
 .admin-contents table.grid tr.admin-flag-item {
   grid-template-columns: auto min-content;
+
+  .d-toggle-switch {
+    margin-right: 0;
+  }
+}
+
+.admin-config-area__primary-content {
+  .admin-flag-form {
+    &__name,
+    &__applies-to.select-kit.multi-select,
+    &__description {
+      width: 100%;
+    }
+  }
 }
diff --git a/app/controllers/admin/config/flags_controller.rb b/app/controllers/admin/config/flags_controller.rb
index 3f1bccdde7e..a95afdf5bce 100644
--- a/app/controllers/admin/config/flags_controller.rb
+++ b/app/controllers/admin/config/flags_controller.rb
@@ -2,7 +2,7 @@
 
 class Admin::Config::FlagsController < Admin::AdminController
   def toggle
-    with_service(ToggleFlag) do
+    with_service(Flags::ToggleFlag) do
       on_success do
         Discourse.request_refresh!
         render(json: success_json)
@@ -19,8 +19,45 @@ class Admin::Config::FlagsController < Admin::AdminController
   def index
   end
 
+  def new
+  end
+
+  def edit
+  end
+
+  def create
+    with_service(Flags::CreateFlag) do
+      on_success do
+        Discourse.request_refresh!
+        render json: result.flag, serializer: FlagSerializer
+      end
+      on_failure { render(json: failed_json, status: 422) }
+      on_failed_policy(:invalid_access) { raise Discourse::InvalidAccess }
+      on_failed_contract do |contract|
+        render(json: failed_json.merge(errors: contract.errors.full_messages), status: 400)
+      end
+    end
+  end
+
+  def update
+    with_service(Flags::UpdateFlag) do
+      on_success do
+        Discourse.request_refresh!
+        render json: result.flag, serializer: FlagSerializer
+      end
+      on_failure { render(json: failed_json, status: 422) }
+      on_model_not_found(:message) { raise Discourse::NotFound }
+      on_failed_policy(:not_system) { render_json_error(I18n.t("flags.errors.system")) }
+      on_failed_policy(:not_used) { render_json_error(I18n.t("flags.errors.used")) }
+      on_failed_policy(:invalid_access) { raise Discourse::InvalidAccess }
+      on_failed_contract do |contract|
+        render(json: failed_json.merge(errors: contract.errors.full_messages), status: 400)
+      end
+    end
+  end
+
   def reorder
-    with_service(ReorderFlag) do
+    with_service(Flags::ReorderFlag) do
       on_success do
         Discourse.request_refresh!
         render(json: success_json)
@@ -34,4 +71,20 @@ class Admin::Config::FlagsController < Admin::AdminController
       end
     end
   end
+
+  def destroy
+    with_service(Flags::DestroyFlag) do
+      on_success do
+        Discourse.request_refresh!
+        render(json: success_json)
+      end
+      on_failure { render(json: failed_json, status: 422) }
+      on_failed_policy(:not_system) { render_json_error(I18n.t("flags.errors.system")) }
+      on_failed_policy(:not_used) { render_json_error(I18n.t("flags.errors.used")) }
+      on_failed_policy(:invalid_access) { raise Discourse::InvalidAccess }
+      on_failed_contract do |contract|
+        render(json: failed_json.merge(errors: contract.errors.full_messages), status: 400)
+      end
+    end
+  end
 end
diff --git a/app/models/flag.rb b/app/models/flag.rb
index 99e1ce5f6d4..ec973008aca 100644
--- a/app/models/flag.rb
+++ b/app/models/flag.rb
@@ -1,7 +1,10 @@
 # frozen_string_literal: true
 
 class Flag < ActiveRecord::Base
+  DEFAULT_VALID_APPLIES_TO = %w[Post Topic]
   MAX_SYSTEM_FLAG_ID = 1000
+  MAX_NAME_LENGTH = 200
+  MAX_DESCRIPTION_LENGTH = 1000
   scope :enabled, -> { where(enabled: true) }
   scope :system, -> { where("id < 1000") }
 
@@ -17,6 +20,10 @@ class Flag < ActiveRecord::Base
       ReviewableScore.exists?(reviewable_score_type: self.id)
   end
 
+  def self.valid_applies_to_types
+    Set.new(DEFAULT_VALID_APPLIES_TO | DiscoursePluginRegistry.flag_applies_to_types)
+  end
+
   def self.reset_flag_settings!
     # Flags are memoized for better performance. After the update, we need to reload them in all processes.
     PostActionType.reload_types
diff --git a/app/models/post_action_type.rb b/app/models/post_action_type.rb
index ff132794c3a..2785215a03c 100644
--- a/app/models/post_action_type.rb
+++ b/app/models/post_action_type.rb
@@ -117,6 +117,14 @@ class PostActionType < ActiveRecord::Base
       all_flags.pluck(:id, :name).to_h
     end
 
+    def descriptions
+      all_flags.pluck(:id, :description).to_h
+    end
+
+    def applies_to
+      all_flags.pluck(:id, :applies_to).to_h
+    end
+
     def is_flag?(sym)
       flag_types.valid?(sym)
     end
diff --git a/app/models/reviewable.rb b/app/models/reviewable.rb
index 3c03fae8a11..0d3846f9e6b 100644
--- a/app/models/reviewable.rb
+++ b/app/models/reviewable.rb
@@ -196,6 +196,11 @@ class Reviewable < ActiveRecord::Base
     update(score: self.score + rs.score, latest_score: rs.created_at, force_review: force_review)
     topic.update(reviewable_score: topic.reviewable_score + rs.score) if topic
 
+    # Flags are cached for performance reasons.
+    # However, when the reviewable item is created, we need to clear the cache to mark flag as used.
+    # Used flags cannot be deleted or update by admins, only disabled.
+    Flag.reset_flag_settings! if PostActionType.notify_flag_type_ids.include?(reviewable_score_type)
+
     DiscourseEvent.trigger(:reviewable_score_updated, self)
 
     rs
diff --git a/app/serializers/post_action_type_serializer.rb b/app/serializers/post_action_type_serializer.rb
index ea2684180ef..8fffc4956ec 100644
--- a/app/serializers/post_action_type_serializer.rb
+++ b/app/serializers/post_action_type_serializer.rb
@@ -10,6 +10,8 @@ class PostActionTypeSerializer < ApplicationSerializer
     :is_flag,
     :is_custom_flag,
     :enabled,
+    :applies_to,
+    :is_used,
   )
 
   include ConfigurableUrls
@@ -27,7 +29,14 @@ class PostActionTypeSerializer < ApplicationSerializer
   end
 
   def description
-    i18n("description", vars: { tos_url:, base_path: Discourse.base_path })
+    i18n(
+      "description",
+      vars: {
+        tos_url:,
+        base_path: Discourse.base_path,
+      },
+      default: object.class.descriptions[object.id],
+    )
   end
 
   def short_description
@@ -42,6 +51,15 @@ class PostActionTypeSerializer < ApplicationSerializer
     !!PostActionType.enabled_flag_types[object.id]
   end
 
+  def applies_to
+    Array.wrap(PostActionType.applies_to[object.id])
+  end
+
+  def is_used
+    PostAction.exists?(post_action_type_id: object.id) ||
+      ReviewableScore.exists?(reviewable_score_type: object.id)
+  end
+
   protected
 
   def i18n(field, default: nil, vars: nil)
diff --git a/app/serializers/reviewable_score_type_serializer.rb b/app/serializers/reviewable_score_type_serializer.rb
index 5737134f9ab..f780cbe7aac 100644
--- a/app/serializers/reviewable_score_type_serializer.rb
+++ b/app/serializers/reviewable_score_type_serializer.rb
@@ -10,8 +10,7 @@ class ReviewableScoreTypeSerializer < ApplicationSerializer
   # Allow us to share post action type translations for backwards compatibility
   def title
     I18n.t("post_action_types.#{type}.title", default: nil) ||
-      I18n.t("reviewable_score_types.#{type}.title", default: nil) ||
-      PostActionType.flag_settings.names[id]
+      I18n.t("reviewable_score_types.#{type}.title", default: nil) || PostActionType.names[id]
   end
 
   def reviewable_priority
diff --git a/app/serializers/site_serializer.rb b/app/serializers/site_serializer.rb
index 20c04c5a696..c25a51e794d 100644
--- a/app/serializers/site_serializer.rb
+++ b/app/serializers/site_serializer.rb
@@ -48,6 +48,7 @@ class SiteSerializer < ApplicationSerializer
     :privacy_policy_url,
     :system_user_avatar_template,
     :lazy_load_categories,
+    :valid_flag_applies_to_types,
   )
 
   has_many :archetypes, embed: :objects, serializer: ArchetypeSerializer
@@ -350,6 +351,14 @@ class SiteSerializer < ApplicationSerializer
     scope.can_lazy_load_categories?
   end
 
+  def valid_flag_applies_to_types
+    Flag.valid_applies_to_types
+  end
+
+  def include_valid_flag_applies_to_types?
+    scope.is_admin?
+  end
+
   private
 
   def ordered_flags(flags)
diff --git a/app/services/flags/create_flag.rb b/app/services/flags/create_flag.rb
new file mode 100644
index 00000000000..5df8f742e69
--- /dev/null
+++ b/app/services/flags/create_flag.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+class Flags::CreateFlag
+  include Service::Base
+
+  contract
+  policy :invalid_access
+  model :flag, :instantiate_flag
+
+  transaction do
+    step :create
+    step :log
+  end
+
+  class Contract
+    attribute :name, :string
+    attribute :description, :string
+    attribute :enabled, :boolean
+    attribute :applies_to
+    validates :name, presence: true
+    validates :description, presence: true
+    validates :name, length: { maximum: Flag::MAX_NAME_LENGTH }
+    validates :description, length: { maximum: Flag::MAX_DESCRIPTION_LENGTH }
+    validates :applies_to, inclusion: { in: Flag.valid_applies_to_types }, allow_nil: false
+  end
+
+  private
+
+  def instantiate_flag(name:, description:, applies_to:, enabled:)
+    Flag.new(
+      name: name,
+      description: description,
+      applies_to: applies_to,
+      enabled: enabled,
+      notify_type: true,
+    )
+  end
+
+  def invalid_access(guardian:)
+    guardian.can_create_flag?
+  end
+
+  def create(flag:)
+    flag.save!
+  end
+
+  def log(guardian:, flag:)
+    StaffActionLogger.new(guardian.user).log_custom(
+      "create_flag",
+      {
+        name: flag.name,
+        description: flag.description,
+        applies_to: flag.applies_to,
+        enabled: flag.enabled,
+      },
+    )
+  end
+end
diff --git a/app/services/flags/destroy_flag.rb b/app/services/flags/destroy_flag.rb
new file mode 100644
index 00000000000..87315c0da85
--- /dev/null
+++ b/app/services/flags/destroy_flag.rb
@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+class Flags::DestroyFlag
+  include Service::Base
+
+  model :flag
+  policy :not_system
+  policy :not_used
+  policy :invalid_access
+
+  transaction do
+    step :destroy
+    step :log
+  end
+
+  private
+
+  def fetch_flag(id:)
+    Flag.find(id)
+  end
+
+  def not_system(flag:)
+    !flag.system?
+  end
+
+  def not_used(flag:)
+    !flag.used?
+  end
+
+  def invalid_access(guardian:, flag:)
+    guardian.can_edit_flag?(flag)
+  end
+
+  def destroy(flag:)
+    flag.destroy!
+  end
+
+  def log(guardian:, flag:)
+    StaffActionLogger.new(guardian.user).log_custom(
+      "delete_flag",
+      {
+        name: flag.name,
+        description: flag.description,
+        applies_to: flag.applies_to,
+        enabled: flag.enabled,
+      },
+    )
+  end
+end
diff --git a/app/services/reorder_flag.rb b/app/services/flags/reorder_flag.rb
similarity index 98%
rename from app/services/reorder_flag.rb
rename to app/services/flags/reorder_flag.rb
index c0e8033f552..a306a7cd32f 100644
--- a/app/services/reorder_flag.rb
+++ b/app/services/flags/reorder_flag.rb
@@ -2,7 +2,7 @@
 
 VALID_DIRECTIONS = %w[up down]
 
-class ReorderFlag
+class Flags::ReorderFlag
   include Service::Base
 
   contract
diff --git a/app/services/toggle_flag.rb b/app/services/flags/toggle_flag.rb
similarity index 96%
rename from app/services/toggle_flag.rb
rename to app/services/flags/toggle_flag.rb
index b30839f649a..d7c65258fd7 100644
--- a/app/services/toggle_flag.rb
+++ b/app/services/flags/toggle_flag.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class ToggleFlag
+class Flags::ToggleFlag
   include Service::Base
 
   contract
diff --git a/app/services/flags/update_flag.rb b/app/services/flags/update_flag.rb
new file mode 100644
index 00000000000..43b0c2f33c1
--- /dev/null
+++ b/app/services/flags/update_flag.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+class Flags::UpdateFlag
+  include Service::Base
+
+  contract
+  model :flag
+  policy :not_system
+  policy :not_used
+  policy :invalid_access
+
+  transaction do
+    step :update
+    step :log
+  end
+
+  class Contract
+    attribute :name, :string
+    attribute :description, :string
+    attribute :enabled, :boolean
+    attribute :applies_to
+    validates :name, presence: true
+    validates :description, presence: true
+    validates :name, length: { maximum: Flag::MAX_NAME_LENGTH }
+    validates :description, length: { maximum: Flag::MAX_DESCRIPTION_LENGTH }
+    validates :applies_to, inclusion: { in: Flag.valid_applies_to_types }, allow_nil: false
+  end
+
+  private
+
+  def fetch_flag(id:)
+    Flag.find(id)
+  end
+
+  def not_system(flag:)
+    !flag.system?
+  end
+
+  def not_used(flag:)
+    !flag.used?
+  end
+
+  def invalid_access(guardian:, flag:)
+    guardian.can_edit_flag?(flag)
+  end
+
+  def update(flag:, name:, description:, applies_to:, enabled:)
+    flag.update!(name: name, description: description, applies_to: applies_to, enabled: enabled)
+  end
+
+  def log(guardian:, flag:)
+    StaffActionLogger.new(guardian.user).log_custom(
+      "update_flag",
+      {
+        name: flag.name,
+        description: flag.description,
+        applies_to: flag.applies_to,
+        enabled: flag.enabled,
+      },
+    )
+  end
+end
diff --git a/config/locales/client.en.yml b/config/locales/client.en.yml
index 2ee0b017ea3..4c7bc56dfb6 100644
--- a/config/locales/client.en.yml
+++ b/config/locales/client.en.yml
@@ -5048,7 +5048,6 @@ en:
           title: "More options"
           move_up: "Move up"
           move_down: "Move down"
-
       groups:
         new:
           title: "New Group"
@@ -5480,6 +5479,36 @@ en:
             contact_information_saved: "Contact information saved"
             your_organization_saved: "Your organization saved"
           saved: "saved!"
+        flags:
+          header: "Moderation Flags"
+          subheader: "The flagging system in Discourse helps you and your moderator team manage content and user behavior, keeping your community respectful and healthy. The defaults are suitable for most communities and you don’t have to change them. However, if your site has particular requirements you can disable flags you don’t need and add your own custom flags."
+          description: "Description"
+          enabled: "Enabled?"
+          add: "Add Flag"
+          edit: "Edit"
+          back: "Back to flags"
+          delete: "Delete"
+          delete_confirm: 'Are you sure you want to delete "%{name}"?'
+          form:
+            add_header: "Add flag"
+            edit_header: "Edit flag"
+            save: "Save"
+            name: "Name"
+            description: "Description"
+            applies_to: "Display this flag on"
+            topic: "topics"
+            post: "posts"
+            chat_message: "chat messages"
+            enabled: "Enable this custom flag after saving"
+            alert: "Once a custom flag has been used, it can only be disabled but not edited or deleted."
+            edit_flag: "Edit flag"
+            non_editable: "You cannot edit this flag because it is a system flag or has already been used in the review system, however you can still disable it."
+            delete_flag: "Delete flag"
+            non_deletable: "You cannot delete this flag because it is a system flag or has already been used in the review system, however you can still disable it."
+          more_options:
+            title: "More options"
+            move_up: "Move up"
+            move_down: "Move down"
       plugins:
         title: "Plugins"
         installed: "Installed Plugins"
@@ -6157,6 +6186,9 @@ en:
             delete_watched_word_group: "delete watched word group"
             toggle_flag: "toggle flag"
             move_flag: "move flag"
+            create_flag: "create flag"
+            update_flag: "update flag"
+            delete_flag: "delete flag"
         screened_emails:
           title: "Screened Emails"
           description: "When someone tries to create a new account, the following email addresses will be checked and the registration will be blocked, or some other action performed."
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 1fbc666964b..69bddef58bd 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -1253,6 +1253,8 @@ en:
     errors:
       already_handled: "Flag was already handled"
       wrong_move: "Flag cannot be moved"
+      system: "System flag cannot be updated or deleted."
+      used: "Flag cannot be updated or deleted because has already been used."
   reports:
     default:
       labels:
diff --git a/config/routes.rb b/config/routes.rb
index 83bb6f961c6..858e551c352 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -386,9 +386,10 @@ Discourse::Application.routes.draw do
         end
       end
       namespace :config, constraints: StaffConstraint.new do
-        resources :flags, only: %i[index] do
+        resources :flags, only: %i[index new create update destroy] do
           put "toggle"
           put "reorder/:direction" => "flags#reorder"
+          member { get "/" => "flags#edit" }
         end
 
         resources :about, constraints: AdminConstraint.new, only: %i[index] do
diff --git a/lib/discourse_plugin_registry.rb b/lib/discourse_plugin_registry.rb
index 98dedcd50ed..cd4dd47b589 100644
--- a/lib/discourse_plugin_registry.rb
+++ b/lib/discourse_plugin_registry.rb
@@ -123,6 +123,8 @@ class DiscoursePluginRegistry
 
   define_filtered_register :problem_checks
 
+  define_filtered_register :flag_applies_to_types
+
   def self.register_auth_provider(auth_provider)
     self.auth_providers << auth_provider
   end
diff --git a/lib/guardian/flag_guardian.rb b/lib/guardian/flag_guardian.rb
index 89cd218bb6a..8d32d651c8e 100644
--- a/lib/guardian/flag_guardian.rb
+++ b/lib/guardian/flag_guardian.rb
@@ -5,6 +5,10 @@ module FlagGuardian
     @user.admin? && !flag.system? && !flag.used?
   end
 
+  def can_create_flag?
+    @user.admin?
+  end
+
   def can_toggle_flag?
     @user.admin?
   end
diff --git a/plugins/chat/assets/javascripts/discourse/lib/chat-message-flag.js b/plugins/chat/assets/javascripts/discourse/lib/chat-message-flag.js
index febcfceddad..e71acd07243 100644
--- a/plugins/chat/assets/javascripts/discourse/lib/chat-message-flag.js
+++ b/plugins/chat/assets/javascripts/discourse/lib/chat-message-flag.js
@@ -37,7 +37,7 @@ export default class ChatMessageFlag {
         "description",
         I18n.t(`chat.flags.${flag.name_key}`, {
           basePath: getURL(""),
-          defaultValue: "",
+          defaultValue: flag.description,
         })
       );
       return flag;
@@ -48,8 +48,9 @@ export default class ChatMessageFlag {
     let flagsAvailable = flagModal.site.flagTypes;
 
     flagsAvailable = flagsAvailable.filter((flag) => {
-      return flagModal.args.model.flagModel.availableFlags.includes(
-        flag.name_key
+      return (
+        flagModal.args.model.flagModel.availableFlags.includes(flag.name_key) &&
+        flag.applies_to.includes("Chat::Message")
       );
     });
 
diff --git a/plugins/chat/plugin.rb b/plugins/chat/plugin.rb
index 797ea11269a..51c3eefdcc5 100644
--- a/plugins/chat/plugin.rb
+++ b/plugins/chat/plugin.rb
@@ -49,6 +49,7 @@ after_initialize do
 
   register_user_custom_field_type(Chat::LAST_CHAT_CHANNEL_ID, :integer)
   DiscoursePluginRegistry.serialized_current_user_fields << Chat::LAST_CHAT_CHANNEL_ID
+  DiscoursePluginRegistry.register_flag_applies_to_type("Chat::Message", self)
 
   UserUpdater::OPTION_ATTR.push(:chat_enabled)
   UserUpdater::OPTION_ATTR.push(:only_chat_push_notifications)
diff --git a/spec/requests/api/schemas/json/site_response.json b/spec/requests/api/schemas/json/site_response.json
index 62b7deeb72a..4a9392ed3ba 100644
--- a/spec/requests/api/schemas/json/site_response.json
+++ b/spec/requests/api/schemas/json/site_response.json
@@ -356,6 +356,12 @@
             },
             "enabled": {
               "type": "boolean"
+            },
+            "applies_to": {
+              "type": "array"
+            },
+            "is_used": {
+              "type": "boolean"
             }
           },
           "required": [
@@ -366,7 +372,9 @@
             "short_description",
             "is_flag",
             "is_custom_flag",
-            "enabled"
+            "enabled",
+            "applies_to",
+            "is_used"
           ]
         }
     },
@@ -400,6 +408,12 @@
             },
             "enabled": {
               "type": "boolean"
+            },
+            "applies_to": {
+              "type": "array"
+            },
+            "is_used": {
+              "type": "boolean"
             }
           },
           "required": [
@@ -410,7 +424,9 @@
             "short_description",
             "is_flag",
             "is_custom_flag",
-            "enabled"
+            "enabled",
+            "applies_to",
+            "is_used"
           ]
         }
     },
@@ -823,6 +839,9 @@
     "denied_emojis" : {
       "type": "array"
     },
+    "valid_flag_applies_to_types" : {
+      "type": "array"
+    },
     "navigation_menu_site_top_tags": {
       "type": "array"
     }
diff --git a/spec/services/flags/create_flag_spec.rb b/spec/services/flags/create_flag_spec.rb
new file mode 100644
index 00000000000..126f4ce3a93
--- /dev/null
+++ b/spec/services/flags/create_flag_spec.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+RSpec.describe(Flags::CreateFlag) do
+  subject(:result) do
+    described_class.call(
+      guardian: current_user.guardian,
+      name: name,
+      description: description,
+      applies_to: applies_to,
+      enabled: enabled,
+    )
+  end
+
+  let(:name) { "custom flag name" }
+  let(:description) { "custom flag description" }
+  let(:applies_to) { ["Topic"] }
+  let(:enabled) { true }
+
+  context "when user is not allowed to perform the action" do
+    fab!(:current_user) { Fabricate(:user) }
+
+    it { is_expected.to fail_a_policy(:invalid_access) }
+  end
+
+  context "when applies to is invalid" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:applies_to) { ["User"] }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when title is empty" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:name) { nil }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when title is too long" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:name) { "a" * 201 }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when description is empty" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:description) { nil }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when description is too long" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:description) { "a" * 1001 }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when user is allowed to perform the action" do
+    fab!(:current_user) { Fabricate(:admin) }
+
+    after { Flag.destroy_by(name: "custom flag name") }
+
+    it "sets the service result as successful" do
+      expect(result).to be_a_success
+    end
+
+    it "creates the flag" do
+      result
+      flag = Flag.last
+      expect(flag.name).to eq("custom flag name")
+      expect(flag.description).to eq("custom flag description")
+      expect(flag.applies_to).to eq(["Topic"])
+      expect(flag.enabled).to be true
+    end
+
+    it "logs the action" do
+      expect { result }.to change { UserHistory.count }.by(1)
+      expect(UserHistory.last).to have_attributes(
+        custom_type: "create_flag",
+        details:
+          "name: custom flag name\ndescription: custom flag description\napplies_to: [\"Topic\"]\nenabled: true",
+      )
+    end
+  end
+end
diff --git a/spec/services/flags/destroy_flag_spec.rb b/spec/services/flags/destroy_flag_spec.rb
new file mode 100644
index 00000000000..cfc2e8b4238
--- /dev/null
+++ b/spec/services/flags/destroy_flag_spec.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+RSpec.describe(Flags::DestroyFlag) do
+  fab!(:flag)
+
+  subject(:result) { described_class.call(id: flag.id, guardian: current_user.guardian) }
+
+  after { flag.destroy }
+
+  context "when user is not allowed to perform the action" do
+    fab!(:current_user) { Fabricate(:user) }
+
+    it { is_expected.to fail_a_policy(:invalid_access) }
+  end
+
+  context "when user is allowed to perform the action" do
+    fab!(:current_user) { Fabricate(:admin) }
+
+    it "sets the service result as successful" do
+      expect(result).to be_a_success
+    end
+
+    it "destroys the flag" do
+      result
+      expect { flag.reload }.to raise_error(ActiveRecord::RecordNotFound)
+    end
+
+    it "logs the action" do
+      expect { result }.to change { UserHistory.count }.by(1)
+      expect(UserHistory.last).to have_attributes(
+        custom_type: "delete_flag",
+        details:
+          "name: offtopic\ndescription: \napplies_to: [\"Post\", \"Chat::Message\"]\nenabled: true",
+      )
+    end
+  end
+end
diff --git a/spec/services/reorder_flag_spec.rb b/spec/services/flags/reorder_flag_spec.rb
similarity index 97%
rename from spec/services/reorder_flag_spec.rb
rename to spec/services/flags/reorder_flag_spec.rb
index cc0e51b3c8b..1eff5f97d4a 100644
--- a/spec/services/reorder_flag_spec.rb
+++ b/spec/services/flags/reorder_flag_spec.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe(ReorderFlag) do
+RSpec.describe(Flags::ReorderFlag) do
   subject(:result) do
     described_class.call(flag_id: flag.id, guardian: current_user.guardian, direction: direction)
   end
diff --git a/spec/services/toggle_flag_spec.rb b/spec/services/flags/toggle_flag_spec.rb
similarity index 96%
rename from spec/services/toggle_flag_spec.rb
rename to spec/services/flags/toggle_flag_spec.rb
index 1cd0f1924d8..4eba4502b58 100644
--- a/spec/services/toggle_flag_spec.rb
+++ b/spec/services/flags/toggle_flag_spec.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe(ToggleFlag) do
+RSpec.describe(Flags::ToggleFlag) do
   subject(:result) { described_class.call(flag_id: flag.id, guardian: current_user.guardian) }
 
   let(:flag) { Flag.system.last }
diff --git a/spec/services/flags/update_flag_spec.rb b/spec/services/flags/update_flag_spec.rb
new file mode 100644
index 00000000000..620a6bbcca9
--- /dev/null
+++ b/spec/services/flags/update_flag_spec.rb
@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+RSpec.describe(Flags::UpdateFlag) do
+  fab!(:flag)
+
+  subject(:result) do
+    described_class.call(
+      id: flag.id,
+      guardian: current_user.guardian,
+      name: name,
+      description: description,
+      applies_to: applies_to,
+      enabled: enabled,
+    )
+  end
+
+  after { flag.destroy }
+
+  let(:name) { "edited custom flag name" }
+  let(:description) { "edited custom flag description" }
+  let(:applies_to) { ["Topic"] }
+  let(:enabled) { false }
+
+  context "when user is not allowed to perform the action" do
+    fab!(:current_user) { Fabricate(:user) }
+
+    it { is_expected.to fail_a_policy(:invalid_access) }
+  end
+
+  context "when applies to is invalid" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:applies_to) { ["User"] }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when title is empty" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:name) { nil }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when title is too long" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:name) { "a" * 201 }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when description is empty" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:description) { nil }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when description is too long" do
+    fab!(:current_user) { Fabricate(:admin) }
+    let(:description) { "a" * 1001 }
+
+    it { is_expected.to fail_a_contract }
+  end
+
+  context "when user is allowed to perform the action" do
+    fab!(:current_user) { Fabricate(:admin) }
+
+    it "sets the service result as successful" do
+      expect(result).to be_a_success
+    end
+
+    it "updates the flag" do
+      result
+      expect(flag.reload.name).to eq("edited custom flag name")
+      expect(flag.description).to eq("edited custom flag description")
+      expect(flag.applies_to).to eq(["Topic"])
+      expect(flag.enabled).to be false
+    end
+
+    it "logs the action" do
+      expect { result }.to change { UserHistory.count }.by(1)
+      expect(UserHistory.last).to have_attributes(
+        custom_type: "update_flag",
+        details:
+          "name: edited custom flag name\ndescription: edited custom flag description\napplies_to: [\"Topic\"]\nenabled: false",
+      )
+    end
+  end
+end
diff --git a/spec/system/admin_flags_spec.rb b/spec/system/admin_flags_spec.rb
index ec5ab7f6580..b37ba6bd785 100644
--- a/spec/system/admin_flags_spec.rb
+++ b/spec/system/admin_flags_spec.rb
@@ -7,6 +7,7 @@ describe "Admin Flags Page", type: :system do
 
   let(:topic_page) { PageObjects::Pages::Topic.new }
   let(:admin_flags_page) { PageObjects::Pages::AdminFlags.new }
+  let(:admin_flag_form_page) { PageObjects::Pages::AdminFlagForm.new }
 
   before { sign_in(admin) }
 
@@ -55,6 +56,55 @@ describe "Admin Flags Page", type: :system do
     )
   end
 
+  it "allows admin to create, edit and delete flags" do
+    topic_page.visit_topic(post.topic)
+    topic_page.open_flag_topic_modal
+    expect(all(".flag-action-type-details strong").map(&:text)).to eq(
+      ["It's Inappropriate", "It's Spam", "It's Illegal", "Something Else"],
+    )
+
+    visit "/admin/config/flags"
+
+    admin_flags_page.click_add_flag
+
+    expect(admin_flag_form_page).to have_disabled_save_button
+
+    admin_flag_form_page.fill_in_name("Vulgar")
+    admin_flag_form_page.fill_in_description("New flag description")
+    admin_flag_form_page.fill_in_applies_to("Topic")
+    admin_flag_form_page.fill_in_applies_to("Post")
+    admin_flag_form_page.click_save
+
+    topic_page.visit_topic(post.topic)
+    topic_page.open_flag_topic_modal
+    expect(all(".flag-action-type-details strong").map(&:text)).to eq(
+      ["It's Inappropriate", "It's Spam", "It's Illegal", "Something Else", "Vulgar"],
+    )
+
+    visit "/admin/config/flags"
+
+    admin_flags_page.click_edit_flag("vulgar")
+
+    admin_flag_form_page.fill_in_name("Tasteless")
+    admin_flag_form_page.click_save
+
+    topic_page.visit_topic(post.topic)
+    topic_page.open_flag_topic_modal
+    expect(all(".flag-action-type-details strong").map(&:text)).to eq(
+      ["It's Inappropriate", "It's Spam", "It's Illegal", "Something Else", "Tasteless"],
+    )
+
+    visit "/admin/config/flags"
+    admin_flags_page.click_delete_flag("tasteless")
+    admin_flags_page.confirm_delete
+
+    topic_page.visit_topic(post.topic)
+    topic_page.open_flag_topic_modal
+    expect(all(".flag-action-type-details strong").map(&:text)).to eq(
+      ["It's Inappropriate", "It's Spam", "It's Illegal", "Something Else"],
+    )
+  end
+
   it "does not allow to move notify user flag" do
     visit "/admin/config/flags"
     expect(page).not_to have_css(".notify_user .flag-menu-trigger")
@@ -66,6 +116,17 @@ describe "Admin Flags Page", type: :system do
     expect(page).not_to have_css(".dropdown-menu__item .move-down")
   end
 
+  it "does not allow to system flag to be edited" do
+    visit "/admin/config/flags"
+    expect(page).to have_css(".off_topic .admin-flag-item__edit[disabled]")
+  end
+
+  it "does not allow to system flag to be deleted" do
+    visit "/admin/config/flags"
+    admin_flags_page.open_flag_menu("notify_moderators")
+    expect(page).to have_css(".admin-flag-item__delete[disabled]")
+  end
+
   it "does not allow top flag to move up" do
     visit "/admin/config/flags"
     admin_flags_page.open_flag_menu("off_topic")
diff --git a/spec/system/page_objects/pages/admin_flag_form.rb b/spec/system/page_objects/pages/admin_flag_form.rb
new file mode 100644
index 00000000000..d923f2a522f
--- /dev/null
+++ b/spec/system/page_objects/pages/admin_flag_form.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Pages
+    class AdminFlagForm < PageObjects::Pages::Base
+      def has_disabled_save_button?
+        find_button("Save", disabled: true)
+      end
+
+      def fill_in_name(name)
+        find(".admin-flag-form__name").fill_in(with: name)
+      end
+
+      def fill_in_description(description)
+        find(".admin-flag-form__description").fill_in(with: description)
+      end
+
+      def fill_in_applies_to(applies_to)
+        dropdown = PageObjects::Components::SelectKit.new(".admin-flag-form__applies-to")
+        dropdown.expand
+        dropdown.select_row_by_value(applies_to)
+        dropdown.collapse
+      end
+
+      def click_save
+        find(".admin-flag-form__save").click
+      end
+    end
+  end
+end
diff --git a/spec/system/page_objects/pages/admin_flags.rb b/spec/system/page_objects/pages/admin_flags.rb
index 6e481c09c59..64724b2e8d0 100644
--- a/spec/system/page_objects/pages/admin_flags.rb
+++ b/spec/system/page_objects/pages/admin_flags.rb
@@ -13,12 +13,29 @@ module PageObjects
 
       def move_down(key)
         open_flag_menu(key)
-        find(".dropdown-menu__item .move-down").click
+        find(".admin-flag-item__move-down").click
       end
 
       def move_up(key)
         open_flag_menu(key)
-        find(".dropdown-menu__item .move-up").click
+        find(".admin-flag-item__move-up").click
+      end
+
+      def click_add_flag
+        find(".admin-flags__header-add-flag").click
+      end
+
+      def click_edit_flag(key)
+        find(".#{key} .admin-flag-item__edit").click
+      end
+
+      def click_delete_flag(key)
+        find(".#{key} .flag-menu-trigger").click
+        find(".admin-flag-item__delete").click
+      end
+
+      def confirm_delete
+        find(".dialog-footer .btn-primary").click
       end
     end
   end