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Open-source neural machine translation library based on OpenNMT's CTranslate2

Project description

Argos Translate

Demo | Website | Docs | Forum | GitHub | PyPI

Open-source offline translation library written in Python

Argos Translate uses OpenNMT for translations and can be used as either a Python library, command-line, or GUI application. Argos Translate supports installing language model packages which are zip archives with a ".argosmodel" extension containing the data needed for translation. LibreTranslate is an API and web-app built on top of Argos Translate.

Argos Translate also manages automatically pivoting through intermediate languages to translate between languages that don't have a direct translation between them installed. For example, if you have a es → en and en → fr translation installed you are able to translate from es → fr as if you had that translation installed. This allows for translating between a wide variety of languages at the cost of some loss of translation quality.

Supported languages

Arabic, Azerbaijani, Catalan, Chinese, Czech, Danish, Dutch, English, Esperanto, Finnish, French, German, Greek, Hebrew, Hindi, Hungarian, Indonesian, Irish, Italian, Japanese, Korean, Persian, Polish, Portuguese, Russian, Slovak, Spanish, Swedish, Turkish, Ukrainian, and more

Request a language


Install with Python

Argos Translate is available from PyPI and can be easily installed or updated with pip.

pip install argostranslate

Install GUI:

pip install argostranslategui

Installation for macOS

  1. Download the latest macOS release.
  2. Extract the archive.
  3. Copy the .app file to the Applications directory.

Python source installation into virtualenv

Download a copy of this repo and install with pip.

git clone
cd argos-translate
virtualenv env
source env/bin/activate
pip install -e .



import argostranslate.package
import argostranslate.translate

from_code = "en"
to_code = "es"

# Download and install Argos Translate package
available_packages = argostranslate.package.get_available_packages()
package_to_install = next(
        lambda x: x.from_code == from_code and x.to_code == to_code, available_packages

# Translate
translatedText = argostranslate.translate.translate("Hello World", from_code, to_code)
# '¡Hola Mundo!'

Command Line Interface

argospm update
argospm install translate-en_de
argos-translate --from en --to de "Hello World!"
# Hallo Welt!

Install all translation packages:

argospm install translate

LibreTranslate Web App (Demo)

Web App Screenshot

LibreTranslate API

const res = await fetch("", {
	method: "POST",
	body: JSON.stringify({
		q: "Hello!",
		source: "en",
		target: "es"
	headers: {
		"Content-Type": "application/json"}

console.log(await res.json());

    "translatedText": "¡Hola!"

Graphical user interface

The GUI code is in a separate repository.

Screenshot Screenshot2 Argos Translate macOS Screenshot


GPU Acceleration

To enable GPU support, you need to set the ARGOS_DEVICE_TYPE env variable to cuda or auto.

$ ARGOS_DEVICE_TYPE=cuda argos-translate --from-lang en --to-lang es "Hello World"
Hola Mundo

The above env variable passes the device type to CTranslate2.

HTML Translation

The translate-html library is built on top of Argos Translate and Beautiful Soup and parses and translates HTML. The LibreTranslate API also has support for translating HTML.

Files Translation

The argos-translate-files library is built on top of Argos Translate and parses and translates files. The LibreTranslate API also has support for translating files.


pip uninstall argostranslate

You may choose to also delete temporary and cached files:

rm -r ~/.local/cache/argos-translate
rm -r ~/.local/share/argos-translate

Related Projects


Contributions are welcome! Available issues are on the GitHub issues page. Contributions of code, data, and pre-trained models can all be accepted.


For support please use the LibreTranslate Forum or GitHub Issues.

For questions about CTranslate2 or general machine translation research the OpenNMT Forum is a good resource.


Custom models trained on your own data are available for $1000/language (negotiable).

I am also available for hire to do support, consulting, or custom software development.


If you find this software useful donations are greatly appreciated and help to make this project sustainable.

  • GitHub Sponsor
  • PayPal
  • Bitcoin: 16UJrmSEGojFPaqjTGpuSMNhNRSsnspFJT
  • Ethereum: argosopentech.eth
  • Litecoin: MCwu7RRWeCRJdsv2bXGj2nnL1xYxDBvwW5
  • BCH: bitcoincash:qzvpxe8y5kq45kahqkyv3p88sjrhlymj2v6xdrj3cv

Paid supporters receive priority support.

Hosting affiliate links

You can help support Argos Translate financially by purchasing hosting through these referral links:

Argos Translate 2 beta

A beta version of Argos Translate 2 is available to install from source from the v2 branch on GitHub. Argos Translate 2 has a multilingual model architecture, more extensive unit testing, and a more experimental orientation.


Contributions are welcome! Bug reports, pull requests, documentation writing, and feature ideas are all appreciated.


Argos Translate is dual licensed under either the MIT License or Creative Commons CC0.

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