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Files

An instance can translate whole documents: plain text, office documents, subtitles, e-books and more. The formats it accepts are in settings().supportedFilesFormat (e.g. .txt, .docx, .pptx, .odt, .epub, .srt, .pdf), and settings().filesTranslation says whether it is enabled at all.

Upload and download​

import { readFile, writeFile } from "node:fs/promises";

const data = await readFile("report.docx");
const { translatedFileUrl } = await lt.translateFile({
  file: new Blob([data]),
  filename: "report.docx",
  source: "en",
  target: "pt",
});

const translated = await lt.downloadFile(translatedFileUrl);
await writeFile(translated.filename, translated.data);
  • file is a Blob or a File. A File brings its own name; a Blob needs filename, because the instance picks the format by the extension.
  • source defaults to auto.
  • translateFile answers the URL the instance serves the result from. downloadFile fetches it as { data: Uint8Array, filename, contentType }, filename coming from the server's Content-Disposition.

An unsupported extension or a disabled feature answers 400 (LibreTranslateApiError).

From an AI agent, libretranslate_translate_file does all of this from a local path and saves the result beside it (see Tools).