> ## Documentation Index > Fetch the complete documentation index at: https://docs.pollo.ai/llms.txt > Use this file to discover all available pages before exploring further. # Kling 4.0 API Documentation > Kling 4.0 API creates up to 30-second videos with stable motion and complex camera movement. Multimodal references and multiple keyframes provide control over characters, scenes, and story progression. Integrate the Kling 4.0 API now. Check out Kling 4.0 API pricing [here](https://api.pollo.ai/pricing?modelName=kling-v4\&modelType=video), cheaper than Fal AI. ## OpenAPI ````yaml POST /v1/generation/kling-ai/kling-v4/video openapi: 3.0.3 info: title: Pollo | AI Video Collection description: >- ✨RESTful API Document. Model discovery: GET /api/v1/model-specs (public, keyless). version: 1.0.0 servers: - url: https://pollo.ai/api/platform security: [] externalDocs: url: https://pollo.ai/api/platform/api/openapi.json paths: /v1/generation/kling-ai/kling-v4/video: post: tags: - Video summary: kling-v4 operationId: v1-kling-ai/kling-v4/video parameters: [] requestBody: required: true content: application/json: schema: type: object required: - input properties: input: oneOf: - type: object properties: prompt: type: string maxLength: 26000 description: Text prompt describing the content to generate. image: type: string description: First-frame / reference image URL (HTTP(S). imageTail: type: string description: Tail (end-frame) image URL duration: type: integer minimum: 3 maximum: 30 default: 10 description: The duration of the generated video, in seconds. resolution: type: string enum: - 720p - 1080p default: 1080p description: >- Output resolution of the generated media (e.g. 720p, 1080p, 2K, 4K). Values are case-insensitive. required: - image title: Image To Video - type: object properties: prompt: type: string maxLength: 26000 minLength: 1 description: Text prompt describing the content to generate. aspectRatio: type: string enum: - '21:9' - '16:9' - '9:16' - '1:1' default: '16:9' description: Output aspect ratio, as width:height (e.g. 16:9). duration: type: integer minimum: 3 maximum: 30 default: 10 description: The duration of the generated video, in seconds. resolution: type: string enum: - 720p - 1080p default: 1080p description: >- Output resolution of the generated media (e.g. 720p, 1080p, 2K, 4K). Values are case-insensitive. required: - prompt title: Text To Video - type: object properties: refs: type: array items: $ref: '#/components/schemas/Ref' maxItems: 15 description: >- Reference items (image / video / audio) for reference-to-video generation. An `audio` item is used as a voice reference: 5–30 s of clean speech from a single speaker (MP3 / WAV, or MP4 / MOV). Mention it in `prompt` as `[@name]` and describe what is said with it. At most 3 voices. prompt: type: string maxLength: 26000 minLength: 1 description: Text prompt describing the content to generate. duration: type: integer minimum: 3 maximum: 30 default: 10 description: The duration of the generated video, in seconds. aspectRatio: type: string enum: - '21:9' - '16:9' - '9:16' - '1:1' - adaptive default: adaptive description: Output aspect ratio, as width:height (e.g. 16:9). resolution: type: string enum: - 720p - 1080p default: 1080p description: >- Output resolution of the generated media (e.g. 720p, 1080p, 2K, 4K). Values are case-insensitive. required: - refs - prompt title: Reference To Video description: >- Constraints: - at most 10 image references are allowed - at most 5 reference videos are allowed (video elements included) - at most 7 elements are allowed, of which at most 3 video elements - at most 3 audio (voice) references are allowed - type: object properties: prompt: type: string maxLength: 26000 description: Text prompt describing the content to generate. keyframes: type: array items: type: object properties: url: type: string format: uri role: type: string enum: - first - middle - last name: type: string maxLength: 64 required: - url maxItems: 10 minItems: 2 description: >- Ordered keyframes for keyframe-to-video. Each item is `{ url, role? }`: `url` is an HTTP(S) image URL; `role` is `first` / `middle` / `last`. When `role` is omitted the first item is the first frame and the rest are middle frames; to start without a first frame, mark the first item `middle`. `first` is only allowed on the first item and `last` only on the last item. Optional `name` lets `prompt` reference a frame as `[@name]` (sent to the model as `@image{n}` by the frame order). duration: type: integer minimum: 3 maximum: 30 default: 10 description: The duration of the generated video, in seconds. resolution: type: string enum: - 720p - 1080p default: 1080p description: >- Output resolution of the generated media (e.g. 720p, 1080p, 2K, 4K). Values are case-insensitive. required: - keyframes title: Keyframes To Video webhookUrl: type: string format: uri description: >- Webhook URL (HTTP(S)) that receives status callbacks when the generation succeeds or fails. responses: '200': description: Successful response content: application/json: schema: type: object properties: taskId: type: string status: type: string enum: - waiting - succeed - failed - processing required: - taskId - status additionalProperties: false '400': $ref: '#/components/responses/ApiError400' '401': $ref: '#/components/responses/ApiError401' '403': $ref: '#/components/responses/ApiError403' '404': $ref: '#/components/responses/ApiError404' '429': $ref: '#/components/responses/ApiError429' '500': $ref: '#/components/responses/ApiError500' default: $ref: '#/components/responses/error' security: - ApiKeyAuth: [] components: schemas: Ref: type: object description: A reference item specifying url / type. properties: url: type: string description: Media URL (HTTP(S)). Required unless `type` is `element`. example: https://example.com/ref.jpg type: type: string enum: - image - video - audio - element description: >- Media kind. Auto-detected from the URL when omitted. `element` references one of your saved elements by `elementId` instead of a URL. name: type: string maxLength: 64 description: >- Mention handle (at most 64 characters, unique within the list); reference this item inside `prompt` as `[@name]`. Defaults to `ref1`, `ref2`… by position, or to the element / variant name for `element` items. elementId: type: string description: >- Only with `type: element`: the element id. Resolves to the element cover image. variantId: type: string description: >- Only with `type: element`: a variant id of that element; uses the variant's active image instead of the cover. ApiError: type: object required: - errorCode - message - code additionalProperties: true properties: errorCode: type: string enum: - REJECTED - INTERNAL - CREDENTIAL_MISSING - CREDENTIAL_INVALID - CLI_TOKEN_EXPIRED - CLI_REFRESH_TOKEN_INVALID - PERMISSION_DENIED - ACCOUNT_SUSPENDED - ACCOUNT_DELETED - CREDITS_INSUFFICIENT - PLAN_FEATURE_REQUIRED - PARALLEL_TASK_LIMIT_REACHED - ACTIVITY_DAILY_LIMIT_REACHED - QUOTA_ELEMENT_FREE - QUOTA_ELEMENT_PAID - QUOTA_BRAND_KIT_FREE - QUOTA_BRAND_KIT_PAID - RATE_LIMIT_EXCEEDED - RATE_LIMIT_PRODUCT_EXTRACT - INPUT_VALIDATION_FAILED - INPUT_NOT_SUPPORTED_BY_MODEL - MODERATION_REJECTED - ASSET_DISABLED_BY_REVIEW - GENERATION_IN_PROGRESS description: >- Stable business error identifier — **the only field to branch on**. Codes are append-only: existing codes are never renamed or repurposed, but new ones are added over time, so treat this as an open set. Match the exact code you handle, else the family prefix (`MODERATION_`, `RATE_LIMIT_`, `QUOTA_`, `ACCOUNT_`, …), else fall back to the HTTP status. message: type: string description: >- Developer-facing text. Varies with locale and product copy — **never match on it**. code: type: string description: >- Transport-level code (tRPC / JSON-RPC naming). Deprecated for business logic; may be removed. requestId: type: string description: Correlation id — quote it when contacting support. issues: type: array description: >- Per-field validation detail. Present when `errorCode` is `INPUT_VALIDATION_FAILED`. items: type: object required: - message additionalProperties: true properties: message: type: string path: type: array items: type: string description: Path to the offending field. responses: ApiError400: description: >- Invalid request — schema validation failed (`INPUT_VALIDATION_FAILED`, detail in `issues`), a cross-field constraint was violated (`INPUT_CONSTRAINT_VIOLATED`), or the input did not pass moderation (`MODERATION_*`). content: application/json: schema: $ref: '#/components/schemas/ApiError' ApiError401: description: >- Missing or invalid credential (`CREDENTIAL_*`, `CLI_TOKEN_EXPIRED`, `EMAIL_LOGIN_REQUIRED`). content: application/json: schema: $ref: '#/components/schemas/ApiError' ApiError403: description: >- Rejected — not enough credits (`CREDITS_INSUFFICIENT`), quota exhausted (`QUOTA_*`), plan required (`PLAN_FEATURE_REQUIRED`), account state (`ACCOUNT_*`), or no permission (`PERMISSION_DENIED`). content: application/json: schema: $ref: '#/components/schemas/ApiError' ApiError404: description: >- Nothing matched — unknown route, model (`MODEL_NOT_FOUND`), task (`TASK_NOT_FOUND`) or asset (`ASSET_NOT_FOUND`). content: application/json: schema: $ref: '#/components/schemas/ApiError' ApiError429: description: >- Rate limited (`RATE_LIMIT_*`). `RATE_LIMIT_MODERATION` means recent content was blocked — adjust the input rather than simply retrying. content: application/json: schema: $ref: '#/components/schemas/ApiError' ApiError500: description: Unexpected server-side failure (`INTERNAL`). content: application/json: schema: $ref: '#/components/schemas/ApiError' error: description: >- Error response. Every failure on this API uses this shape; branch on `errorCode`. content: application/json: schema: $ref: '#/components/schemas/ApiError' securitySchemes: ApiKeyAuth: type: apiKey in: header name: x-api-key description: API key to authorize requests ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.