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File Inputs

You can attach files inline to POST /v1/chat/completions and POST /v1/messages requests, in each API's standard shape. Any chat model can answer questions about them, except the end-to-end encrypted models: when the provider serving the request cannot read files itself, the Router extracts the text and puts it in the message where you attached the file.

Supported formats are PDF (with a text layer) and UTF-8 text files such as .txt, .md, .csv, .json or source code. The format is detected from the file's content, not from its name or declared MIME type.

Request​

Send the file as base64, either as a data: URI or as bare base64.

curl https://router-api.0g.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer sk-YOUR_API_KEY" \
  -d '{
    "model": "deepseek-v4-flash",
    "messages": [{
      "role": "user",
      "content": [
        {"type": "text", "text": "What is the new launch date in these notes?"},
        {"type": "file", "file": {
          "filename": "notes.txt",
          "file_data": "data:text/plain;base64,TWVldGluZyBub3RlcwpEZWNpc2lvbjogbGF1bmNoIGRhdGUgbW92ZWQgdG8gMjAyNi0xMS0xNS4K"
        }}
      ]
    }]
  }'

For a PDF, use data:application/pdf;base64,....

The file name (filename, or title on /v1/messages) is shown to the model with the file's text, so give it a meaningful name.

How the file is read​

  • Provider reads files itself. The file is forwarded unchanged and the provider reads it, including content the Router cannot extract, such as scanned pages.
  • Otherwise, the Router extracts the text. Each file is replaced by a text part holding its content, between [File: <name>] and [End of file: <name>] markers. The response's x_0g_trace.request_rewritten then contains "file_parse":
"x_0g_trace": {
  "request_id": "096a7a44-a82d-4a3d-b84b-b9528ddffb3c",
  "request_rewritten": ["file_parse"]
}

Because the provider received a modified request, its TEE signature will not match the request you sent when request_rewritten is present.

End-to-end encrypted models​

Requests to 0gm-1.0-35b-a3b and glm-5.3 are encrypted before they reach the Router, so the Router cannot read the file or extract its text. The file reaches the provider unchanged, and the provider rejects the request with a 400 error. To ask about a file with these models, paste its text into the message instead, or use another model, such as glm-5.3-flash.

Limits​

The limits and errors below apply when the Router extracts the text. When the provider reads files itself, the file is forwarded as sent and the provider decides what it accepts.

LimitValue
Files per request20, counted across all messages, including files attached in earlier turns
Text kept per file200,000 bytes; the rest is cut and the model is told the file was truncated

The request body is limited to 20 MiB, after base64 encoding, on every /v1/chat/completions and /v1/messages request, whoever reads the file. A larger body fails with 413 and payload_too_large when its Content-Length header shows the size, or with 400 and invalid_request when it is sent chunked.

Files are not stored: send the file again in every request that needs it, as in a normal conversation history.

Errors​

A file the Router cannot read fails the request with 400 and invalid_request_error, rather than letting the model answer without it. The message names the file.

codeCause
unsupported_file_typeThe file is neither a PDF nor UTF-8 text (for example an image, a .docx or a .zip)
file_parse_failedThe PDF has no extractable text (a scanned PDF; OCR is not supported), or is damaged or encrypted
unsupported_file_sourceThe file is given by file_id, by URL, or by an Anthropic source.type other than base64. Only inline base64 data is accepted
invalid_file_dataThe file data is empty or not valid base64
too_many_filesMore than 20 files in the request

These errors are not charged.

Billing​

There is no fee for files. When the Router extracts the text, that text is billed as input tokens at the model's normal price. When the provider reads the file itself, you pay the input tokens the provider reports for it.

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