FileObject

OpenAI-shaped file object. Field names match OpenAI's FileObject, plus a mime_type extension carrying the byte-sniffed content type.

idstringrequired

Opaque file id, always prefixed file_. Referenced from a Responses-API request as an input_file content part.

Example: file_8pauo0KQA-g_Bi7LHx5RA

objectstringrequired

OpenAI discriminator; always the literal file.

Constant value: file

bytesintegerrequired

Size of the file in bytes.

Example: 18342

created_atintegerrequired

Unix timestamp (seconds) at which the file was created.

Example: 1718900000

filenamestringrequired

The (sanitized) original filename.

Example: quarterly-report.docx

purposeFilePurpose (string)required

Intended use of the file. Mirrors OpenAI's Files API purpose. Only user_data is accepted in v1; the other OpenAI purposes (assistants, batch, fine-tune, vision) are reserved and rejected.

Possible values: [user_data]

Example: user_data

mime_typestringrequired

The MIME type detected from the file's magic-number bytes (not the upload's Content-Type header).

Example: application/vnd.openxmlformats-officedocument.wordprocessingml.document

FileObject

{
  "id": "file_8pauo0KQA-g_Bi7LHx5RA",
  "object": "file",
  "bytes": 18342,
  "created_at": 1718900000,
  "filename": "quarterly-report.docx",
  "purpose": "user_data",
  "mime_type": "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
}