diff --git a/docker-compose.yml b/docker-compose.yml
index 1aa5238d0ad..ac389b8f82a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -97,7 +97,7 @@ services:
     volumes:
       - "pgdata:/var/lib/postgresql/data"
     ports:
-      - "54322:5432"
+      - "5432:5432"
     environment:
       POSTGRES_USER: ${DB_USERNAME:-postgres}
       POSTGRES_PASSWORD: ${DB_PASSWORD:-postgres}
@@ -119,7 +119,7 @@ services:
     volumes:
       - "pgdata-test:/var/lib/postgresql/data"
     ports:
-      - "5432:5432"
+      - "5433:5432"
     environment:
       POSTGRES_DB: openproject
       POSTGRES_USER: openproject
diff --git a/docker/dev/backend/Dockerfile b/docker/dev/backend/Dockerfile
index bf24d5171a4..88060437fc1 100644
--- a/docker/dev/backend/Dockerfile
+++ b/docker/dev/backend/Dockerfile
@@ -23,7 +23,12 @@ WORKDIR /home/$USER
 
 RUN apt-get update -qq && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y \
-    postgresql-client libffi7 libffi-dev
+    postgresql-client libffi7 libffi-dev curl
+
+# Setup node source and install nodejs. Needed for running certain scripts in backend container,
+# as the `./scripts/api/validate_spec`.
+RUN curl -fsSL https://deb.nodesource.com/setup_14.x | bash -
+RUN apt-get install -y nodejs
 
 COPY ./docker/dev/backend/scripts/setup /usr/sbin/setup
 COPY ./docker/dev/backend/scripts/run-app /usr/sbin/run-app
diff --git a/docs/api/apiv3/components/schemas/attachments_by_post.yml b/docs/api/apiv3/components/schemas/attachments_by_post.yml
deleted file mode 100644
index 8cb9eed5c37..00000000000
--- a/docs/api/apiv3/components/schemas/attachments_by_post.yml
+++ /dev/null
@@ -1,2 +0,0 @@
-# Schema: Attachments_by_post
---- {}
diff --git a/docs/api/apiv3/components/schemas/attachments_by_post_model.yml b/docs/api/apiv3/components/schemas/attachments_by_post_model.yml
deleted file mode 100644
index ac77d405900..00000000000
--- a/docs/api/apiv3/components/schemas/attachments_by_post_model.yml
+++ /dev/null
@@ -1,2 +0,0 @@
-# Schema: Attachments_by_postModel
---- {}
diff --git a/docs/api/apiv3/components/schemas/attachments_by_wiki_page.yml b/docs/api/apiv3/components/schemas/attachments_by_wiki_page.yml
deleted file mode 100644
index 398c2f7c1cc..00000000000
--- a/docs/api/apiv3/components/schemas/attachments_by_wiki_page.yml
+++ /dev/null
@@ -1,2 +0,0 @@
-# Schema: Attachments_by_wiki_page
---- {}
diff --git a/docs/api/apiv3/components/schemas/attachments_by_wiki_page_model.yml b/docs/api/apiv3/components/schemas/attachments_by_wiki_page_model.yml
deleted file mode 100644
index a26b035a101..00000000000
--- a/docs/api/apiv3/components/schemas/attachments_by_wiki_page_model.yml
+++ /dev/null
@@ -1,2 +0,0 @@
-# Schema: Attachments_by_wiki_pageModel
---- {}
diff --git a/docs/api/apiv3/components/schemas/attachments_by_work_package.yml b/docs/api/apiv3/components/schemas/attachments_by_work_package.yml
deleted file mode 100644
index 6ccfbed78b7..00000000000
--- a/docs/api/apiv3/components/schemas/attachments_by_work_package.yml
+++ /dev/null
@@ -1,2 +0,0 @@
-# Schema: Attachments_by_work_package
---- {}
diff --git a/docs/api/apiv3/components/schemas/attachments_by_work_package_model.yml b/docs/api/apiv3/components/schemas/attachments_by_work_package_model.yml
deleted file mode 100644
index 1200c89a231..00000000000
--- a/docs/api/apiv3/components/schemas/attachments_by_work_package_model.yml
+++ /dev/null
@@ -1,2 +0,0 @@
-# Schema: Attachments_by_work_packageModel
---- {}
diff --git a/docs/api/apiv3/components/schemas/file_link_collection_read_model.yml b/docs/api/apiv3/components/schemas/file_link_collection_read_model.yml
index e9b0cb55a30..6d59d113724 100644
--- a/docs/api/apiv3/components/schemas/file_link_collection_read_model.yml
+++ b/docs/api/apiv3/components/schemas/file_link_collection_read_model.yml
@@ -16,9 +16,9 @@ allOf:
             allOf:
               - $ref: "./link.yml"
               - description: |-
-                  This file links list
+                  This file links collection
                   
-                  **Resource**: File_LinksModel
+                  **Resource**: FileLinkCollectionReadModel
       _embedded:
         type: object
         required:
diff --git a/docs/api/apiv3/components/schemas/list_notifications_model.yml b/docs/api/apiv3/components/schemas/list_notifications_model.yml
deleted file mode 100644
index b5880c53932..00000000000
--- a/docs/api/apiv3/components/schemas/list_notifications_model.yml
+++ /dev/null
@@ -1,43 +0,0 @@
-# Schema: List_notificationsModel
----
-type: object
-example:
-  _type: Collection
-  _embedded:
-    elements:
-      - _links:
-          readIAN:
-            href: "/api/v3/notifications/1/read_ian"
-            method: "post"
-          actor:
-            href: "/api/v3/users/2"
-            title: Peggie Feeney
-          activity:
-            href: "/api/v3/activities/1234"
-          project:
-            href: "/api/v3/projects/1"
-            title: Seeded Project
-          self:
-            href: "/api/v3/notifications/1"
-        _type: Notification
-        createdAt: "2021-07-20T08:32:18Z"
-        updatedAt: "2021-07-20T08:33:19Z"
-        id: 1
-        reason: mentioned
-        subject: "You have been mentioned in Task #1234 An important task"
-    _links:
-      changeSize:
-        href: "/api/v3/notifications?offset=1&pageSize=%7Bsize%7D"
-        templated: true
-      jumpTo:
-        href: "/api/v3/notifications?offset=%7Boffset%7D&pageSize=2"
-        templated: true
-      nextByOffset:
-        href: "/api/v3/notifications?offset=2&pageSize=2"
-      self:
-        href: "/api/v3/notifications?offset=1&pageSize=2"
-    _type: Collection
-    count: 1
-    offset: 1
-    pageSize: 50
-    total: 1
diff --git a/docs/api/apiv3/components/schemas/notification_collection_model.yml b/docs/api/apiv3/components/schemas/notification_collection_model.yml
new file mode 100644
index 00000000000..1f3e3054dd2
--- /dev/null
+++ b/docs/api/apiv3/components/schemas/notification_collection_model.yml
@@ -0,0 +1,70 @@
+# Schema: NotificationCollectionModel
+---
+allOf:
+  - $ref: './collection_model.yml'
+  - type: object
+    required:
+      - _links
+      - _embedded
+    properties:
+      _links:
+        type: object
+        required:
+          - self
+        properties:
+          self:
+            allOf:
+              - $ref: "./link.yml"
+              - description: |-
+                  This notification collection
+                  
+                  **Resource**: NotificationCollectionModel
+          jumpTo:
+            allOf:
+              - $ref: "./link.yml"
+              - description: |-
+                  The notification collection at another offset
+                  
+                  **Resource**: NotificationCollectionModel
+          changeSize:
+            allOf:
+              - $ref: "./link.yml"
+              - description: |-
+                  The notification collection with another size
+                  
+                  **Resource**: NotificationCollectionModel
+      _embedded:
+        type: object
+        required:
+          - elements
+        properties:
+          elements:
+            type: array
+            items:
+              $ref: './notification_model.yml'
+
+example:
+  _type: Collection
+  count: 2
+  total: 2
+  offset: 1
+  pageSize: 20
+  _embedded:
+    elements:
+      - _hint: Notification resource shortened for brevity
+        id: 1
+        readIAN: false
+        reason: mentioned
+      - _hint: Notification resource shortened for brevity
+        id: 2
+        readIAN: false
+        reason: mentioned
+    _links:
+      self:
+        href: '/api/v3/notifications?offset=1&pageSize=20'
+      jumpTo:
+        href: '/api/v3/notifications?filters=%5B%5D&offset=%7Boffset%7D&pageSize=20'
+        templated: true
+      changeSize:
+        href: '/api/v3/notifications?filters=%5B%5D&offset=1&pageSize=%7Bsize%7D'
+        templated: true
\ No newline at end of file
diff --git a/docs/api/apiv3/components/schemas/notification_model.yml b/docs/api/apiv3/components/schemas/notification_model.yml
index 2e9a537fe2e..22a1a1c6f64 100644
--- a/docs/api/apiv3/components/schemas/notification_model.yml
+++ b/docs/api/apiv3/components/schemas/notification_model.yml
@@ -2,65 +2,81 @@
 ---
 type: object
 properties:
+  _type:
+    type: string
+    enum:
+      - Notification
   id:
     type: integer
     description: Notification id
-    readOnly: true
-    minimum: 0
-    exclusiveMinimum: true
-  subject:
-    type: string
-    description: The subject of the notification
-    readOnly: true
+    minimum: 1
   reason:
     type: string
     description: The reason for the notification (such as mentioned, involved, watched)
-    readOnly: true
   readIAN:
     type: boolean
     description: Whether the notification is marked as read
-    readOnly: true
   createdAt:
     type: string
     format: date-time
     description: The time the notification was created at
-    readOnly: true
   updatedAt:
     type: string
     format: date-time
     description: The time the notification was last updated
-    readOnly: true
+  _embedded:
+    type: object
+    required:
+      - actor
+      - project
+      - activity
+      - resource
+    properties:
+      actor:
+        $ref: './user_model.yml'
+      project:
+        $ref: './project_model.yml'
+      activity:
+        $ref: './activity_model.yml'
+      resource:
+        oneOf:
+          - $ref: './work_package_model.yml'
   _links:
     type: object
     required:
-    - self
-    - project
-    - actor
+      - self
+      - readIAN
+      - project
+      - actor
+      - activity
+      - resource
     properties:
       self:
         allOf:
-        - "$ref": "./link.yml"
-        - description: |-
-            This notification
-
-            **Resource**: Notification
-          readOnly: true
+          - "$ref": "./link.yml"
+          - description: |-
+              This notification
+              
+              **Resource**: Notification
+      readIAN:
+        allOf:
+          - "$ref": "./link.yml"
+          - description: |-
+              Request to mark the notification as read.
       project:
         allOf:
-        - "$ref": "./link.yml"
-        - description: |-
-            The project the notification originated in
-
-            **Resource**: Project
-          readOnly: true
+          - "$ref": "./link.yml"
+          - description: |-
+              The project the notification originated in
+              
+              **Resource**: Project
       actor:
         allOf:
-        - "$ref": "./link.yml"
-        - description: |-
-            The user that caused the notification
-
-            **Resource**: User
-          readOnly: true
+          - "$ref": "./link.yml"
+          - description: |-
+              The user that caused the notification
+              
+              **Resource**: User
       resource:
         allOf:
           - "$ref": "./link.yml"
@@ -68,7 +84,6 @@ properties:
               The linked resource of the notification, if any.
 
               **Resource**: Polymorphic
-            readOnly: true
       activity:
         allOf:
           - "$ref": "./link.yml"
@@ -76,38 +91,48 @@ properties:
               The journal activity, if the notification originated from a journal entry
 
               **Resource**: Activity
-            readOnly: true
 example:
-  _type: News
+  _type: Notification
   id: 1
-  title: asperiores possimus nam doloribus ab
-  summary: Celebrer spiculum colo viscus claustrum atque. Id nulla culpa sumptus.
-    Comparo crapula depopulo demonstro.
-  description:
-    format: markdown
-    raw: Videlicet deserunt aequitas cognatus. Concedo quia est quia pariatur vorago
-      vallum. Calco autem atavus accusamus conscendo cornu ulterius. Tam patria ago
-      consectetur ventito sustineo nihil caecus. Supra officiis eos velociter somniculosus
-      tonsor qui. Suffragium aduro arguo angustus cogito quia tolero vulnus. Supplanto
-      sortitus cresco apud vestrum qui.
-    html: "<p>Videlicet deserunt aequitas cognatus. Concedo quia est quia pariatur
-      vorago vallum. Calco autem atavus accusamus conscendo cornu ulterius. Tam patria
-      ago consectetur ventito sustineo nihil caecus. Supra officiis eos velociter
-      somniculosus tonsor qui. Suffragium aduro arguo angustus cogito quia tolero
-      vulnus. Supplanto sortitus cresco apud vestrum qui.</p>"
-  createdAt: '2015-03-20T12:57:01Z'
+  readIAN: false
+  reason: mentioned
+  createdAt: '2022-04-05T14:38:28Z'
+  updatedAt: '2022-04-06T09:03:24Z'
+  _embedded:
+    author:
+      _hint: User resource shortened for brevity
+      _type: User
+      id: 13
+      name: Darth Nihilus
+    project:
+      _hint: Project resource shortened for brevity
+      _type: Project
+      id: 11
+      name: Jedi Remnant Locator
+    activity:
+      _hint: Activity resource shortened for brevity
+      _type: Activity::Comment
+      id: 180
+      version: 3
+    resource:
+      _hint: WorkPackage resource shortened for brevity
+      _type: WorkPackage
+      id: 77
+      subject: Educate Visas Marr
   _links:
     self:
-      href: "/api/v3/news/1"
-      title: asperiores possimus nam doloribus ab
+      href: '/api/v3/notifications/1'
+    readIAN:
+      href: '/api/v3/notifications/1/read_ian'
+      method: post
+    actor:
+      href: '/api/v3/users/13'
+      title: Darth Nihilus
     project:
-      href: "/api/v3/projects/1"
-      title: A project
-    author:
-      href: "/api/v3/users/2"
-      title: Peggie Feeney
-  _embedded:
-    project:
-      _type: Project...
-    author:
-      _type: User...
+      href: '/api/v3/projects/11'
+      title: Jedi Remnant Locator
+    activity:
+      href: '/api/v3/activities/180'
+    resource:
+      href: '/api/v3/work_packages/77'
+      title: Educate Visas Marr
diff --git a/docs/api/apiv3/openapi-spec.yml b/docs/api/apiv3/openapi-spec.yml
index de9faca7c69..bd9611685ab 100644
--- a/docs/api/apiv3/openapi-spec.yml
+++ b/docs/api/apiv3/openapi-spec.yml
@@ -555,8 +555,6 @@ components:
       "$ref": "./components/schemas/list_memberships_model.yml"
     List_of_NewsModel:
       "$ref": "./components/schemas/list_of_news_model.yml"
-    List_notificationsModel:
-      "$ref": "./components/schemas/list_notifications_model.yml"
     List_projectsModel:
       "$ref": "./components/schemas/list_projects_model.yml"
     List_projects_by_versionModel:
@@ -577,6 +575,8 @@ components:
       "$ref": "./components/schemas/membership_update_form.yml"
     NewsModel:
       "$ref": "./components/schemas/news_model.yml"
+    NotificationCollectionModel:
+      "$ref": "./components/schemas/notification_collection_model.yml"
     NotificationModel:
       "$ref": "./components/schemas/notification_model.yml"
     NotificationSettingsModel:
diff --git a/docs/api/apiv3/paths/file_link.yml b/docs/api/apiv3/paths/file_link.yml
index 261fa14a082..c33cb4cfffc 100644
--- a/docs/api/apiv3/paths/file_link.yml
+++ b/docs/api/apiv3/paths/file_link.yml
@@ -2,7 +2,7 @@
 ---
 get:
   summary: Gets a file link.
-  operationId: Work_Package_Get_File_Link
+  operationId: Get_File_Link
   tags:
     - Work Packages
     - File links
diff --git a/docs/api/apiv3/paths/notification.yml b/docs/api/apiv3/paths/notification.yml
index 1587aa9a1d1..337f98164a1 100644
--- a/docs/api/apiv3/paths/notification.yml
+++ b/docs/api/apiv3/paths/notification.yml
@@ -1,40 +1,36 @@
 # /api/v3/notifications/{id}
 ---
 get:
+  summary: Get the notification
+  operationId: Get_Notification
+  tags:
+    - Notifications
+  description: Returns the notification identified by the notification id.
   parameters:
-  - description: notification id
-    example: '1'
-    in: path
-    name: id
-    required: true
-    schema:
-      type: integer
+    - name: id
+      in: path
+      description: notification id
+      example: '1'
+      required: true
+      schema:
+        type: integer
   responses:
     '200':
       content:
         application/hal+json:
           schema:
-            "$ref": "../components/schemas/notification_model.yml"
+            $ref: '../components/schemas/notification_model.yml'
       description: OK
-      headers: {}
     '404':
       content:
         application/hal+json:
           schema:
-            $ref: "../components/schemas/error_response.yml"
-          examples:
-            response:
-              value:
-                _type: Error
-                errorIdentifier: urn:openproject-org:api:v3:errors:NotFound
-                message: The requested resource could not be found.
+            $ref: '../components/schemas/error_response.yml'
+          example:
+            _type: Error
+            errorIdentifier: urn:openproject-org:api:v3:errors:NotFound
+            message: The requested resource could not be found.
       description: |-
         Returned if the notification does not exist or if the user does not have permission to view it.
 
         **Required permission** being recipient of the notification
-      headers: {}
-  tags:
-  - Notifications
-  description: ''
-  operationId: View_notification
-  summary: View notification
diff --git a/docs/api/apiv3/paths/notifications.yml b/docs/api/apiv3/paths/notifications.yml
index 47a434e9280..e7639722fb4 100644
--- a/docs/api/apiv3/paths/notifications.yml
+++ b/docs/api/apiv3/paths/notifications.yml
@@ -1,23 +1,33 @@
 # /api/v3/notifications
 ---
 get:
+  summary: Get notification collection
+  operationId: Get_Notification_Collection
+  tags:
+    - Notifications
+  description: |-
+    Returns the collection of available in-app notifications. The notifications returned depend on the provided
+    parameters and also on the requesting user's permissions.
   parameters:
-    - description: Page number inside the requested collection.
-      example: '25'
+    - name: offset
+      description: Page number inside the requested collection.
       in: query
-      name: offset
+      example: 25
       required: false
       schema:
         default: 1
         type: integer
-    - description: Number of elements to display per page.
-      example: '25'
+    - name: pageSize
+      description: Number of elements to display per page.
       in: query
-      name: pageSize
+      example: 25
       required: false
       schema:
+        default: 20
         type: integer
-    - description: |-
+    - name: sortBy
+      in: query
+      description: |-
         JSON specifying sort criteria.
         Accepts the same format as returned by the [queries](https://www.openproject.org/docs/api/endpoints/queries/) endpoint. Currently supported sorts are:
 
@@ -27,24 +37,24 @@ get:
 
         + readIAN: Sort by read status
       example: '[["reason", "asc"]]'
-      in: query
-      name: sortBy
       required: false
       schema:
         type: string
-    - description: |-
+    - name: groupBy
+      in: query
+      description: |-
         string specifying group_by criteria.
 
         + reason: Group by notification reason
 
         + project: Sort by associated project
       example: 'reason'
-      in: query
-      name: groupBy
       required: false
       schema:
         type: string
-    - description: |-
+    - name: filters
+      in: query
+      description: |-
         JSON specifying filter conditions.
         Accepts the same format as returned by the [queries](https://www.openproject.org/docs/api/endpoints/queries/) endpoint. Currently supported filters are:
 
@@ -60,8 +70,6 @@ get:
 
         + resourceType: Filter by the type of the resource the notification was created for. Ideally used together with the `resourceId` filter.
       example: '[{ "readIAN": { "operator": "=", "values": ["t"] } }]'
-      in: query
-      name: filters
       required: false
       schema:
         type: string
@@ -70,39 +78,26 @@ get:
       content:
         application/hal+json:
           schema:
-            "$ref": "../components/schemas/list_notifications_model.yml"
+            $ref: '../components/schemas/notification_collection_model.yml'
       description: OK
-      headers: { }
     '400':
       content:
         application/hal+json:
           schema:
-            $ref: "../components/schemas/error_response.yml"
-          examples:
-            response:
-              value:
-                _type: Error
-                errorIdentifier: urn:openproject-org:api:v3:errors:InvalidQuery
-                message:
-                  - Filters Invalid filter does not exist.
+            $ref: '../components/schemas/error_response.yml'
+          example:
+            _type: Error
+            errorIdentifier: urn:openproject-org:api:v3:errors:InvalidQuery
+            message:
+              - Filters Invalid filter does not exist.
       description: Returned if the client sends invalid request parameters e.g. filters
-      headers: { }
     '403':
       content:
         application/hal+json:
           schema:
-            $ref: "../components/schemas/error_response.yml"
-          examples:
-            response:
-              value:
-                _type: Error
-                errorIdentifier: urn:openproject-org:api:v3:errors:MissingPermission
-                message: You are not authorized to view this resource.
+            $ref: '../components/schemas/error_response.yml'
+          example:
+            _type: Error
+            errorIdentifier: urn:openproject-org:api:v3:errors:MissingPermission
+            message: You are not authorized to view this resource.
       description: Returned if the client is not logged in and login is required.
-      headers: { }
-  tags:
-    - Notifications
-  description: Lists available in-app notifications. The notifications returned depend on the provided parameters and
-    also on the requesting user's permissions.
-  operationId: List_Notifications
-  summary: List Notifications