> ## Documentation Index > Fetch the complete documentation index at: https://docs.tracks.alpic.ai/llms.txt > Use this file to discover all available pages before exploring further. # Request a file upload > Request with `name`, `content_type` and exact byte `size`, e.g. `{"name":"photo.png","content_type":"image/png","size":12345}`. Any type of file, up to 20 MiB each. PUT raw bytes (not JSON or base64) to the returned `url` with every returned header within 15 minutes; browsers set `content-length` from the body. Uploads are write-once; repeating the PUT returns 412. Pass the returned `id` in `input_files` when creating a run. Files in the landing zone expire after 24 hours and are deleted asynchronously. Files attached to a run are retained permanently and their references can be reused by your organization. ## OpenAPI ````yaml https://tracks.alpic.ai/api/openapi.json post /files openapi: 3.1.0 info: title: Tracks API version: 0.0.1 description: >- Run coding agents such as Claude Code in isolated sandboxes with an API key of your organization. Create a run with a prompt, then follow its output and what it costs, or launch an experiment to compare agents on your scenarios. servers: - url: https://tracks.alpic.ai/api security: [] tags: - name: Runs description: Start coding agents and follow their work. - name: Files description: Upload files to place in a run's sandbox. - name: Connections description: >- Let agents use MCP servers as one of their users, without their credentials entering the sandbox. - name: Experiments description: >- Define scenarios to give several agents in several variants, judged on what they did. - name: Executions description: Launch experiments and read their results. - name: Library description: What your experiments can give their agents. - name: System paths: /files: post: tags: - Files summary: Request a file upload description: >- Request with `name`, `content_type` and exact byte `size`, e.g. `{"name":"photo.png","content_type":"image/png","size":12345}`. Any type of file, up to 20 MiB each. PUT raw bytes (not JSON or base64) to the returned `url` with every returned header within 15 minutes; browsers set `content-length` from the body. Uploads are write-once; repeating the PUT returns 412. Pass the returned `id` in `input_files` when creating a run. Files in the landing zone expire after 24 hours and are deleted asynchronously. Files attached to a run are retained permanently and their references can be reused by your organization. operationId: files.createUpload parameters: [] requestBody: content: application/json: schema: type: object properties: name: type: string description: >- Filename, without directories; up to 128 ASCII letters, digits, spaces, dots, hyphens or underscores, starting with a letter or digit. content_type: type: string description: >- MIME type, without parameters; `application/octet-stream` when unknown. size: type: integer minimum: 1 maximum: 20971520 description: Exact size in bytes, from 1 to 20 MiB. required: - name - content_type - size additionalProperties: false required: true responses: '201': description: Success content: application/json: schema: type: object properties: id: type: string description: Reference returned when requesting a file upload. url: type: string method: type: string enum: - PUT headers: type: object additionalProperties: type: string upload_expires_at: type: string expires_at: type: string required: - id - url - method - headers - upload_expires_at - expires_at additionalProperties: false '400': description: >- The request is invalid: a value is missing, has the wrong type or is out of range. Fix it before sending the request again. content: application/json: schema: $ref: '#/components/schemas/InvalidRequestEncoded' '401': description: >- The API key is missing, malformed or revoked, or its organization is closed. content: application/json: schema: $ref: '#/components/schemas/ApiKeyRefusedEncoded' security: - bearer: [] components: schemas: InvalidRequestEncoded: type: object properties: _tag: type: string enum: - InvalidRequest message: type: string description: Every problem found, in one sentence. location: type: string enum: - path - query - header - body description: The part of the request that is wrong. issues: type: array items: $ref: '#/components/schemas/RequestIssue' description: Each problem found, with where it is. required: - _tag - message - location - issues additionalProperties: false ApiKeyRefusedEncoded: type: object properties: _tag: type: string enum: - ApiKeyRefused message: type: string required: - _tag - message additionalProperties: false RequestIssue: type: object properties: path: type: array items: anyOf: - type: string - type: number - type: string enum: - Infinity - '-Infinity' - NaN description: >- Keys leading to the wrong value inside that part of the request, such as `["agent", "model"]`. Empty when the problem concerns that part as a whole. message: type: string description: What is wrong with the value. required: - path - message additionalProperties: false description: One problem found in the request. securitySchemes: bearer: description: >- An API key of your organization, starting with `trk_`, sent as `Authorization: Bearer `. type: http scheme: bearer ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.