Lingo.dev is an open-source suite of localization engineering tools that connects codebases and commits to translation APIs, built for developers and teams maintaining multilingual JavaScript, React, React Native, and TypeScript applications.

What it is

Lingo.dev is an open-source collection of localization engineering tools written in TypeScript and released under the Apache-2.0 licence. It lives in the i18n tooling space of the JavaScript and React ecosystem and bundles several distinct pieces: the Lingo API, the Lingo React MCP, the Lingo CLI, the Lingo GitHub Action, and the Lingo Compiler for React, which is currently in early alpha. The tools connect to localization engines on the Lingo.dev platform, which are stateful translation APIs that persist glossaries, brand voice, and per-locale instructions across requests, or they can be pointed at a large language model of your own choosing.

The concrete problem it solves is that setting up internationalization in React applications is error-prone, and even AI coding assistants hallucinate non-existent APIs and break routing when left to configure it unaided. Alongside that, conventional workflows force teams to hand-manage translation keys, JSON files, and t() function calls as strings change over time. The Lingo CLI addresses this with a lockfile that tracks what has already been localized, so only new or changed content gets processed.

Key capabilities

• The Lingo CLI localizes JSON, YAML, markdown, CSV, and PO files in a single command, run as npx lingo.dev@latest init followed by npx lingo.dev@latest run.
• It can bring your own LLM through OpenAI, Anthropic, Google, Mistral, OpenRouter, or Ollama, or default to a localization engine hosted on Lingo.dev.
• The Lingo GitHub Action is declared as uses: lingodotdev/lingo.dev@main with an api-key secret, and it runs continuous localization in GitHub Actions, GitLab CI/CD, and Bitbucket Pipelines.
• The Lingo React MCP gives AI assistants structured access to framework-specific i18n knowledge for Next.js, React Router, and TanStack Start, and works with Claude Code, Cursor, GitHub Copilot Agents, and Codex.
• The Lingo API supports synchronous and asynchronous localization with webhook delivery, failure isolation per locale, and real-time progress through WebSocket.
• The Lingo Compiler for React, in early alpha, uses a withLingo() plugin for build-time localization without i18n wrappers, plus no translation keys, no JSON files, and no t() functions, targeting Next.js App Router and Vite with React.
• Localization engines persist glossaries, brand voice, and per-locale instructions, which the README reports as reducing terminology errors by 16.6 to 44.6 percent.

Who uses it and how

• React developers who want an AI assistant such as Cursor or Claude Code to set up i18n, using the MCP prompt "Set up i18n" instead of hand-writing configuration.
• Teams practicing continuous localization, where every push to GitHub, GitLab, or Bitbucket triggers localization so missing strings are filled before code reaches production.
• Backend teams that call a localization engine directly from their code, using asynchronous requests and webhook delivery to localize without blocking a request path.
• Projects that need to localize mixed content types, processing JSON, YAML, markdown, CSV, and PO files together through the CLI.
• Teams that prefer to route translation through their own model provider, including Ollama for locally hosted models.

Getting started

Install and run the CLI with npx lingo.dev@latest init and npx lingo.dev@latest run, or add continuous localization to a pipeline with the GitHub Action declared as uses: lingodotdev/lingo.dev@main and an api-key secret. Both routes connect to a localization engine on Lingo.dev or to a model provider you supply.

How it compares

The facts provided do not include a list of paid products that Lingo.dev replaces, and no directly comparable localization tool is named in the registry entry. On the evidence available, it stands alone in this registry rather than being charted against named alternatives.

When to use it — and when not to

The tools depend on reaching a translation backend, either an engine hosted on Lingo.dev or an external model provider such as OpenAI, Anthropic, Google, Mistral, OpenRouter, or Ollama, so anyone who needs translation with no outbound API access or no key management will need to plan for that dependency. Contributing to the project itself means working inside a pnpm and turborepo monorepo with its own build and test steps. The Compiler for React is explicitly early alpha, so teams needing stable, fully supported build-time localization should treat that piece with caution, and the tools work best for JavaScript and React projects rather than other language ecosystems.

npx lingo.dev@latest init
npx lingo.dev@latest run

uses: lingodotdev/lingo.dev@main
with:
  api-key: ${{ secrets.LINGODOTDEV_API_KEY }}