Files

The files endpoint stores a file once so you can reference it by id in any number of chat requests instead of re-encoding the bytes into every message. It follows the OpenAI files schema, so the openai SDK's files methods work without modification. Uploads and storage are free.

Upload a file#

import fs from "node:fs";
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://opendunes.com/api/v1",
  apiKey: process.env.OPENDUNES_API_KEY,
});

const file = await client.files.create({
  file: fs.createReadStream("report.pdf"),
  purpose: "user_data",
});

console.log(file.id); // reference this id in chat requests

Reference it in a chat request#

Send a file content part carrying the file_id — the server inlines the bytes for you:

const completion = await client.chat.completions.create({
  model: "google/gemini-2.5-flash",
  messages: [
    {
      role: "user",
      content: [
        { type: "text", text: "Summarize this document." },
        { type: "file", file: { file_id: file.id } },
      ],
    },
  ],
});

Notes#

• Max 32 MB per file, 256 MB storage per account; files expire after 30 days.
• Supported types: images (png, jpeg, webp, gif), audio (mp3, wav, flac, m4a, ogg, aac), PDF, and plain text.
• The model must support the file's modality — vision for images, audio input for audio, file/PDF input for documents.
• List, retrieve, and delete are also available — see the Files guide for the full surface.

Also see#

• Files guide — endpoints, limits, and reference semantics
• Files reference