> ## Documentation Index > Fetch the complete documentation index at: https://heygen-1fa696a7.mintlify.app/llms.txt > Use this file to discover all available pages before exploring further. # Upload Asset > Uploads a file (image, video, audio, or PDF) and returns an asset_id for use in other endpoints. Max 32 MB. Supported types: png, jpeg, mp4, webm, mp3, wav, pdf. ## OpenAPI ````yaml /openapi/external-api.json post /v3/assets openapi: 3.1.0 info: title: HeyGen External API version: 1.0.0 description: >- HeyGen's external API for programmatic AI video creation. See https://docs.heygen.com for full documentation. contact: name: HeyGen Product Infra url: https://heygen.com servers: - url: https://api.heygen.com description: Production security: - ApiKeyAuth: [] - BearerAuth: [] tags: - name: Video Agent description: Create videos from text prompts using AI - name: Videos description: Create, list, retrieve, and delete videos - name: Voices description: Text-to-speech and voice management - name: Audio description: Search the background-music and sound-effects catalog - name: Video Translate description: Translate videos into other languages - name: User description: Account information and billing - name: Avatars description: List and manage avatars and looks - name: Assets description: Upload files for use in video creation - name: Webhooks description: Manage webhook endpoints and events - name: Lipsync description: Dub or replace audio on existing videos - name: Brand description: >- Brand-related resources — brand kits (colors, fonts, logos) and brand glossaries (custom term translations) paths: /v3/assets: post: tags: - Assets summary: Upload Asset description: >- Uploads a file (image, video, audio, or PDF) and returns an asset_id for use in other endpoints. Max 32 MB. Supported types: png, jpeg, mp4, webm, mp3, wav, pdf. operationId: uploadAsset parameters: - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: multipart/form-data: schema: type: object properties: file: type: string format: binary description: File to upload (image, video, audio, or PDF). Max 32 MB. required: - file responses: '200': description: Successful response content: application/json: schema: type: object properties: data: $ref: '#/components/schemas/UploadAssetV3Response' '400': description: Invalid request parameters content: application/json: schema: type: object properties: error: $ref: '#/components/schemas/StandardAPIError' example: error: code: invalid_parameter message: File is required. Upload a file using multipart/form-data. param: file doc_url: null '401': description: Authentication failed content: application/json: schema: type: object properties: error: $ref: '#/components/schemas/StandardAPIError' example: error: code: authentication_failed message: Invalid or expired API key. Verify your x-api-key header. param: null doc_url: null '409': $ref: '#/components/responses/IdempotencyInProgress' '429': description: Rate limit exceeded content: application/json: schema: type: object properties: error: $ref: '#/components/schemas/StandardAPIError' example: error: code: rate_limit_exceeded message: >- Too many requests. Retry after the duration specified in the Retry-After header. param: null doc_url: null headers: Retry-After: description: Seconds to wait before retrying schema: type: integer security: - ApiKeyAuth: [] - BearerAuth: [] components: parameters: IdempotencyKey: name: Idempotency-Key in: header required: false description: >- Optional client-supplied key for safely retrying mutations. Subsequent calls within 24 hours that share this key replay the original response — even if the request body differs slightly (a warning is logged). A retry that arrives while the original is still in flight gets a 409 `request_in_progress`. Keys must be 1–255 characters from `[A-Za-z0-9_:.-]`; a UUID is a safe default. Scope is per-endpoint and per-resource: the same key on a different route or path parameter is independent. schema: type: string pattern: ^[A-Za-z0-9_\-:.]{1,255}$ maxLength: 255 minLength: 1 example: 550e8400-e29b-41d4-a716-446655440000 schemas: UploadAssetV3Response: description: Response from uploading an asset via POST /v3/assets. properties: asset_id: description: >- Unique asset identifier for use in other endpoints like POST /v3/video-agents title: Asset Id type: string url: description: Public URL of the uploaded asset title: Url type: string mime_type: description: Detected MIME type of the file title: Mime Type type: string size_bytes: description: File size in bytes title: Size Bytes type: integer required: - asset_id - url - mime_type - size_bytes title: UploadAssetV3Response type: object StandardAPIError: type: object properties: code: type: string description: Machine-readable error code example: invalid_parameter message: type: string description: Human-readable error message example: Video not found param: type: - string - 'null' description: Which request field caused the error doc_url: type: - string - 'null' description: Link to error documentation required: - code - message responses: IdempotencyInProgress: description: >- A prior request with this Idempotency-Key is still in progress. Wait for the original request to complete, then retry. content: application/json: schema: type: object properties: error: $ref: '#/components/schemas/StandardAPIError' example: error: code: request_in_progress message: >- A request with this Idempotency-Key is already in progress. Retry shortly. param: null doc_url: null securitySchemes: ApiKeyAuth: type: apiKey in: header name: x-api-key description: HeyGen API key. Obtain from your HeyGen dashboard. BearerAuth: type: http scheme: bearer description: OAuth2 bearer token. ````