Open-source Gengo alternatives

LibreTranslate is a machine translation API that you can run entirely on your own server. Unlike hosted translation APIs, it does not depend on proprietary services such as Google or Azure. Its translation engine is the open-source Argos Translate library, and the project is licensed under AGPL-3.0.

It provides a web interface for translating text and files, along with an API documented on the site. The homepage lists languages including Basque, Chinese, English, French, German, Irish, Japanese, Russian and Spanish, among others. The software can work offline and is designed to be set up in a few minutes.

A hosted instance is available at libretranslate.com, with an option to obtain an API key, while developers who prefer control over their data can download the software and run their own API server. It is written in Python, and a Quickstart guide and community resources explain deployment.

Lingo.dev is a set of open-source localization engineering tools that connect to the Lingo.dev platform. It is aimed at product teams that translate their software into multiple languages and want that work to be consistent, measurable and automated, instead of passing strings around by hand.

On the platform, teams configure localization engines with glossaries, brand voice and per-locale chains of language models, and call them from code, the command line, CI/CD pipelines or MCP. Quality criteria that teams define in plain words are used to score translations from LLMs and from native speakers, so low-scoring languages can be found and traced back to a model, a rule or a missing glossary term.

The open-source repository, written in TypeScript and licensed under Apache-2.0, includes a command-line tool and a compiler package, and its topics point to React and React Native projects. A hosted platform with sign-in, pricing and enterprise options sits alongside it.