Sending files

Upload a file once via the Files API and reference it by file_id on Chat Completions or Responses, or send it inline — base64-encoded directly in the request — on Chat Completions only.

Field reference

	Responses API	Chat Completions
Part type	`input_file`	`file`
Inline base64	Not supported	`file_data`
Uploaded file	`file_id` (required)	`file_id`

Inline base64

Inline file_data is Chat Completions only. Include a text part with your instruction, then one or more file parts for the documents.

curl --request POST \
  --url https://api.subq.ai/v1/chat/completions \
  --header "Authorization: Bearer $SUBQ_API_KEY" \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "subq-preview",
  "messages": [
    {
      "role": "user",
      "content": [
        {
          "type": "text",
          "text": "Summarize these documents."
        },
        {
          "type": "file",
          "filename": "financial-report-2026.pdf",
          "mime_type": "application/pdf",
          "file_data": "JVBERi0xLjcKJdDUxdgK..."
        },
        {
          "type": "file",
          "filename": "board-deck-q1.pdf",
          "mime_type": "application/pdf",
          "file_data": "JVBERi0xLjcKJdDUxdgK..."
        },
        {
          "type": "file",
          "filename": "meeting-notes.txt",
          "mime_type": "text/plain",
          "file_data": "U3ViUSBkb2N1bWVudCBub3Rlcy4uLg=="
        }
      ]
    }
  ]
}
'

cURLTypeScriptPython

Set file_data to the base64-encoded file content — plain, with no line wrapping. Do not use a data URL prefix such as data:application/pdf;base64,.

File part

Field	Type	Required	Description
`type`	string	Yes	Must be `"file"`.
`filename`	string	No	Recommended. File name to associate with the document, such as `financial-report-2026.pdf` or `meeting-notes.txt`.
`mime_type`	string	Yes	MIME type for the file, such as `"application/pdf"` or `"text/plain"`.
`file_data`	string	Yes	Base64-encoded file content.

Accepted file types

Set mime_type to match the file you send.

Category	Extensions	MIME type
PDF	`.pdf`	`application/pdf`
Plain text	`.txt`	`text/plain`
Markdown	`.md`	`text/markdown`
CSV	`.csv`	`text/csv`
TSV	`.tsv`	`text/tab-separated-values`
JSON	`.json`	`application/json`
XML	`.xml`	`application/xml` or `text/xml`

Word (.doc/.docx) and JSONL aren't accepted inline — upload them and pass file_id instead. See Files API for the full uploaded-file format list.

Non-text formats need to finish processing first — wait for status to reach processed before referencing them. See Files API for upload mechanics, visibility, and the rest of the file lifecycle. Responses does not accept inline file_data; see Responses input.

Choosing an approach

	Inline base64	Uploaded file
Sent as	`file_data` on the request	`file_id` from an earlier upload
Extra request	None	`POST /v1/files` once per file
Reuse	Re-sends the bytes every time	Reference the same `file_id` repeatedly
Accepted formats	PDF, plain text, Markdown, CSV, TSV, JSON, and XML	Adds JSONL and Word (`.doc`/`.docx`)
Size	Bounded by your request size	50 MB per file
Lifetime	Request-scoped	Stored per organization until deleted

Inline base64 is the shortest path for a one-off Chat Completions request. Upload the file instead when you are calling Responses, when the same document is used across several requests, when it is large, or when it is a format inline input does not accept.

Response handling

Once a file's status is processed, its content is available to the model for that request — the reply is ordinary assistant text, the same as any other turn. Combine with Structured outputs to extract specific fields from the document instead of a free-text summary.

Files API — upload, list, retrieve, and delete stored files.
Chat Completions API — file parts on messages.
Responses API — input_file parts on input.
Models — supported model IDs.