Dify Completion Messages API

openapi: 3.0.1
info:
  title: Dify Completion Messages API
  description: REST API for Dify applications and knowledge bases. Application endpoints authenticate
    with an app API key; knowledge endpoints authenticate with a dataset API key.
  version: 1.0.0
servers:
- url: https://{api_base_url}
  description: Base URL of the Dify Service API. For self-hosted deployments, replace it with your own
    API base URL.
  variables:
    api_base_url:
      default: api.dify.ai/v1
      description: Host and path of the API base URL, without the `https://` prefix.
security:
- ApiKeyAuth: []
tags:
- name: Completion Messages
  description: Operations related to text generation and completion.
paths:
  /completion-messages:
    post:
      summary: Send Completion Message
      description: '**Available for**: Text Generator apps.


        Sends a request to a text-generation app and returns the generated text.'
      operationId: createCompletionMessage
      tags:
      - Completion Messages
      requestBody:
        description: Request body to create a completion message.
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CompletionRequest'
            examples:
              streaming_example:
                summary: Request Example - Streaming mode
                value:
                  inputs:
                    city: San Francisco
                  query: Translate 'hello' to Spanish.
                  response_mode: streaming
                  user: abc-123
                  files:
                  - type: image
                    transfer_method: remote_url
                    url: https://cloud.dify.ai/logo/logo-site.png
              blocking_example:
                summary: Request Example - Blocking mode
                value:
                  inputs:
                    city: New York
                  query: 'Summarize the following text: ...'
                  response_mode: blocking
                  user: def-456
      responses:
        '200':
          description: 'Successful response. The content type and structure depend on the `response_mode`
            parameter in the request.


            - If `response_mode` is `blocking`, returns `application/json` with a `CompletionResponse`
            object.

            - If `response_mode` is `streaming`, returns `text/event-stream` with a stream of `ChunkCompletionEvent`
            objects.'
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CompletionResponse'
              examples:
                blockingResponse:
                  summary: Response Example - Blocking mode
                  value:
                    event: message
                    task_id: c3800678-a077-43df-a102-53f23ed20b88
                    id: b01a39de-3480-4f3e-9f1e-4841a80f8e5e
                    message_id: 9da23599-e713-473b-982c-4328d4f5c78a
                    mode: completion
                    answer: Hello World!...
                    metadata:
                      usage:
                        prompt_tokens: 1033
                        prompt_unit_price: '0.001'
                        prompt_price_unit: '0.001'
                        prompt_price: '0.0010330'
                        completion_tokens: 128
                        completion_unit_price: '0.002'
                        completion_price_unit: '0.001'
                        completion_price: '0.0002560'
                        total_tokens: 1161
                        total_price: '0.0012890'
                        currency: USD
                        latency: 0.7682376249867957
                    created_at: 1705407629
            text/event-stream:
              schema:
                type: string
                description: 'A stream of Server-Sent Events. Parse it per the [SSE Streaming guide](/en/api-reference/guides/streaming):
                  read `data:` lines, dispatch on the `event` field, skip `ping` (keep-alive every 10
                  seconds). See `ChunkCompletionEvent` for the event structures.


                  **Stream lifecycle**: the reply streams as `message` chunks and ends with `message_end`.
                  An `error` event ends the stream early; HTTP status stays `200`, so inspect the event
                  payload for details.'
              examples:
                streamingResponse:
                  summary: Response Example - Streaming mode
                  value: 'data: {"event": "message", "task_id": "900bbd43-dc0b-4383-a372-aa6e6c414227",
                    "message_id": "5ad4cb98-f0c7-4085-b384-88c403be6290", "answer": " I", "created_at":
                    1679586595}


                    data: {"event": "message", "task_id": "900bbd43-dc0b-4383-a372-aa6e6c414227", "message_id":
                    "5ad4cb98-f0c7-4085-b384-88c403be6290", "answer": "''m", "created_at": 1679586595}


                    data: {"event": "message_end", "task_id": "900bbd43-dc0b-4383-a372-aa6e6c414227",
                    "id": "5e52ce04-874b-4d27-9045-b3bc80def685", "message_id": "5ad4cb98-f0c7-4085-b384-88c403be6290",
                    "metadata": {"usage": {"prompt_tokens": 1033, "prompt_unit_price": "0.001", "prompt_price_unit":
                    "0.001", "prompt_price": "0.0010330", "completion_tokens": 135, "completion_unit_price":
                    "0.002", "completion_price_unit": "0.001", "completion_price": "0.0002700", "total_tokens":
                    1168, "total_price": "0.0013030", "currency": "USD", "latency": 1.381760165997548}}}


                    '
        '400':
          description: '- `app_unavailable` : App unavailable or misconfigured.

            - `provider_not_initialize` : No valid model provider credentials found.

            - `provider_quota_exceeded` : Model provider quota exhausted.

            - `model_currently_not_support` : Current model unavailable.

            - `completion_request_error` : Text generation failed.

            - `invalid_param` : The required `user` field is missing.'
          content:
            application/json:
              examples:
                app_unavailable:
                  summary: app_unavailable
                  value:
                    status: 400
                    code: app_unavailable
                    message: App unavailable, please check your app configurations.
                provider_not_initialize:
                  summary: provider_not_initialize
                  value:
                    status: 400
                    code: provider_not_initialize
                    message: No valid model provider credentials found. Please go to Settings -> Model
                      Provider to complete your provider credentials.
                provider_quota_exceeded:
                  summary: provider_quota_exceeded
                  value:
                    status: 400
                    code: provider_quota_exceeded
                    message: Your quota for Dify Hosted OpenAI has been exhausted. Please go to Settings
                      -> Model Provider to complete your own provider credentials.
                model_currently_not_support:
                  summary: model_currently_not_support
                  value:
                    status: 400
                    code: model_currently_not_support
                    message: Dify Hosted OpenAI trial currently not support the GPT-4 model.
                completion_request_error:
                  summary: completion_request_error
                  value:
                    status: 400
                    code: completion_request_error
                    message: Completion request failed.
                invalid_param:
                  summary: invalid_param
                  value:
                    status: 400
                    code: invalid_param
                    message: Arg user must be provided.
        '429':
          description: '`too_many_requests` : Too many concurrent requests for this app.'
          content:
            application/json:
              examples:
                too_many_requests:
                  summary: too_many_requests
                  value:
                    status: 429
                    code: too_many_requests
                    message: Too many requests. Please try again later. The current maximum concurrent
                      requests allowed for 5b3d4f2a-1c9e-4a7b-8f6d-2e0c9a1b3d4f is 10.
        '500':
          description: '`internal_server_error` : Internal server error.'
          content:
            application/json:
              examples:
                internal_server_error:
                  summary: internal_server_error
                  value:
                    status: 500
                    code: internal_server_error
                    message: The server encountered an internal error and was unable to complete your
                      request. Either the server is overloaded or there is an error in the application.
      x-mint:
        href: /en/api-reference/completion-messages/send-completion-message
        metadata:
          title: Send Completion Message
          sidebarTitle: Send Completion Message
  /completion-messages/{task_id}/stop:
    post:
      summary: Stop Completion Message Generation
      description: '**Available for**: Text Generator apps.


        Stops a completion message generation task. Only supported in `streaming` mode.'
      operationId: stopGenerate
      tags:
      - Completion Messages
      parameters:
      - name: task_id
        in: path
        required: true
        description: Task ID, from the streaming events of [Send Completion Message](/en/api-reference/completion-messages/send-completion-message).
        schema:
          type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
              - user
              properties:
                user:
                  type: string
                  description: End-user identifier, defined by your app and unique within it. Must match
                    the `user` sent with the original message; if it differs, the stop silently does nothing
                    and still returns success. See [End User Identity](/en/api-reference/guides/end-user-identity).
            examples:
              example:
                summary: Request Example
                value:
                  user: abc-123
      responses:
        '200':
          $ref: '#/components/responses/SuccessResult'
        '400':
          description: '- `app_unavailable` : App unavailable or misconfigured.

            - `invalid_param` : The required `user` field is missing.'
          content:
            application/json:
              examples:
                app_unavailable:
                  summary: app_unavailable
                  value:
                    status: 400
                    code: app_unavailable
                    message: App unavailable, please check your app configurations.
                invalid_param:
                  summary: invalid_param
                  value:
                    status: 400
                    code: invalid_param
                    message: Arg user must be provided.
      x-mint:
        href: /en/api-reference/completion-messages/stop-completion-message-generation
        metadata:
          title: Stop Completion Message Generation
          sidebarTitle: Stop Completion Message Generation
components:
  responses:
    SuccessResult:
      description: Operation successful.
      content:
        application/json:
          schema:
            type: object
            properties:
              result:
                type: string
                description: Operation result. Always `success`.
          examples:
            success:
              summary: Response Example
              value:
                result: success
  schemas:
    CompletionRequest:
      type: object
      required:
      - inputs
      - user
      properties:
        inputs:
          type: object
          description: Values for the app's input variables, keyed by variable name. The expected names
            and types come from the `user_input_form` field of [Get App Parameters](/en/api-reference/applications/get-app-parameters).
          additionalProperties: true
        query:
          type: string
          default: ''
          description: The text to process. Legacy field; newer apps pass this inside `inputs` instead.
        response_mode:
          type: string
          enum:
          - streaming
          - blocking
          description: Mode of response return. `streaming` (recommended) uses SSE. `blocking` returns
            after completion (may be interrupted for long processes). Cloudflare timeout is `100 s`. When
            omitted, defaults to blocking behavior.
        user:
          type: string
          description: End-user identifier, defined by your app and unique within it. Messages and files
            are visible only to requests carrying the same `user`. See [End User Identity](/en/api-reference/guides/end-user-identity).
        files:
          type: array
          items:
            $ref: '#/components/schemas/InputFileObject'
          description: 'Files to attach to the request. For a local file, first upload it via [Upload
            File](/en/api-reference/files/upload-file), then reference the returned `id` as `upload_file_id`
            with `transfer_method: local_file`.'
    CompletionResponse:
      type: object
      properties:
        event:
          type: string
          description: Event type, fixed as `message`.
        task_id:
          type: string
          format: uuid
          description: Task ID for request tracking and the [Stop Completion Message Generation](/en/api-reference/completion-messages/stop-completion-message-generation)
            API.
        id:
          type: string
          format: uuid
          description: Unique ID of this response event.
        message_id:
          type: string
          format: uuid
          description: Unique message ID. Use this as the `message_id` parameter when calling feedback
            or suggested questions endpoints.
        mode:
          type: string
          description: App mode, fixed as `completion`.
        answer:
          type: string
          description: Complete response content.
        metadata:
          type: object
          description: Metadata including usage and retriever resources.
          properties:
            usage:
              $ref: '#/components/schemas/Usage'
            retriever_resources:
              type: array
              description: List of retriever resources used.
              items:
                $ref: '#/components/schemas/RetrieverResource'
        created_at:
          type: integer
          format: int64
          description: Message creation timestamp (Unix epoch seconds).
    InputFileObject:
      type: object
      required:
      - type
      - transfer_method
      properties:
        type:
          type: string
          enum:
          - image
          - document
          - audio
          - video
          - custom
          description: File type.
        transfer_method:
          type: string
          enum:
          - remote_url
          - local_file
          description: 'Transfer method: `remote_url` for file URL, `local_file` for uploaded file.'
        url:
          type: string
          format: url
          description: File URL (when `transfer_method` is `remote_url`).
        upload_file_id:
          type: string
          description: Uploaded file ID, obtained by uploading through the [Upload File](/en/api-reference/files/upload-file)
            API in advance (when `transfer_method` is `local_file`).
      anyOf:
      - properties:
          transfer_method:
            enum:
            - remote_url
          url:
            type: string
            format: url
        required:
        - url
        not:
          required:
          - upload_file_id
      - properties:
          transfer_method:
            enum:
            - local_file
          upload_file_id:
            type: string
        required:
        - upload_file_id
        not:
          required:
          - url
    RetrieverResource:
      type: object
      description: Citation and attribution information for a retriever resource.
      properties:
        id:
          type: string
          format: uuid
          description: Unique ID of the retriever resource.
        message_id:
          type: string
          format: uuid
          description: ID of the message this resource belongs to.
        position:
          type: integer
          description: Position of the resource in the list.
        dataset_id:
          type: string
          format: uuid
          description: ID of the knowledge base.
        dataset_name:
          type: string
          description: Name of the knowledge base.
        document_id:
          type: string
          format: uuid
          description: ID of the document.
        document_name:
          type: string
          description: Name of the document.
        data_source_type:
          type: string
          description: Type of the data source.
        segment_id:
          type: string
          format: uuid
          description: ID of the specific chunk within the document.
        score:
          type: number
          format: float
          description: Similarity score of the resource.
        hit_count:
          type: integer
          description: Number of times this chunk was hit.
        word_count:
          type: integer
          description: Word count of the chunk.
        segment_position:
          type: integer
          description: Position of the chunk within the document.
        index_node_hash:
          type: string
          description: Hash of the index node.
        content:
          type: string
          description: Content snippet from the resource.
        summary:
          type: string
          nullable: true
          description: Summary of the chunk content.
        created_at:
          type: integer
          format: int64
          description: Creation timestamp (Unix epoch seconds).
    Usage:
      type: object
      description: Model usage information.
      properties:
        prompt_tokens:
          type: integer
          description: Number of tokens in the prompt.
        prompt_unit_price:
          type: string
          format: decimal
          description: Unit price per prompt token.
        prompt_price_unit:
          type: string
          format: decimal
          description: Price unit for prompt tokens.
        prompt_price:
          type: string
          format: decimal
          description: Total price for prompt tokens.
        completion_tokens:
          type: integer
          description: Number of tokens in the completion.
        completion_unit_price:
          type: string
          format: decimal
          description: Unit price per completion token.
        completion_price_unit:
          type: string
          format: decimal
          description: Price unit for completion tokens.
        completion_price:
          type: string
          format: decimal
          description: Total price for completion tokens.
        total_tokens:
          type: integer
          description: Total number of tokens used.
        total_price:
          type: string
          format: decimal
          description: Total price for all tokens.
        currency:
          type: string
          description: Currency for pricing.
        latency:
          type: number
          format: double
          description: Latency in seconds.
  securitySchemes:
    ApiKeyAuth:
      type: http
      scheme: bearer
      bearerFormat: API_KEY
      description: 'Every request authenticates with an API key: `Authorization: Bearer {API_KEY}`. App
        endpoints take an app API key; knowledge endpoints take a knowledge base API key ([Get Started](/en/api-reference/guides/get-started)).


        Keep keys server-side; never embed them in client code. Requests with a missing or invalid key
        fail with HTTP `401` (`unauthorized`).'
x-provenance:
  generated: '2026-09-06'
  method: derived
  source: openapi/_original/dify-service-api-openapi.json
  note: Per-tag split of the first-party Dify Service API OpenAPI harvested from https://docs.dify.ai/en/api-reference/openapi_service.json
    (advertised in https://docs.dify.ai/llms.txt). Paths, schemas and operationIds are verbatim from that
    spec.