Visual Studio CodeVS Code Extension available! Install now

Translate Browser extension messages.json files online

Upload your .json files to SimpleLocalize, add languages, auto-translate and download one .json file per language in seconds.

Translate Extension JSON file
No credit card required•14-day free trial•Tracking-free service
{ "appName": { "message": "My Extension", "description": "The name of the extension" }, "greeting": { "message": "Hello, $USER$!", "description": "Greets the user", "placeholders": { "user": { "content": "$1", "example": "John" } } } }
{
  "appName": {
    "message": "My Extension",
    "description": "The name of the extension"
  },
  "greeting": {
    "message": "Hello, $USER$!",
    "description": "Greets the user",
    "placeholders": {
      "user": {
        "content": "$1",
        "example": "John"
      }
    }
  }
}

What is the Browser extension messages.json format?

The _locales/xx/messages.json format used by Chrome, Firefox and Edge extensions. Every key holds a message and an optional description for translators.

It is used by Chrome extensions, Firefox add-ons, Edge extensions. SimpleLocalize reads and writes it natively, so you keep your existing project structure. Format value for the CLI and API: browser-extension-json. Read the format documentation.

How to translate Browser extension messages.json files

  1. Create a free account and a project. The Community plan covers small apps with no credit card.
  2. Import your .json file in the web editor, or push it from the terminal with the CLI.
  3. Add target languages and run auto-translation. Use DeepL or Google Translate for speed, or OpenAI, Claude and Gemini with your own API key for context-aware translations.
  4. Review in the editor with QA checks, glossary and screenshots, then download the Extension JSON files or publish them to the translation hosting CDN.

Sync Extension JSON files from CI

Add a simplelocalize.yml to the repository and run simplelocalize upload and simplelocalize download in your pipeline or GitHub Action:

# simplelocalize.yml apiKey: YOUR_PROJECT_API_KEY uploadFormat: browser-extension-json uploadPath: ./locales/{lang}.json downloadFormat: browser-extension-json downloadPath: ./locales/{lang}.json
# simplelocalize.yml
apiKey: YOUR_PROJECT_API_KEY
uploadFormat: browser-extension-json
uploadPath: ./locales/{lang}.json
downloadFormat: browser-extension-json
downloadPath: ./locales/{lang}.json

Convert Extension JSON to other formats

The same project can export translations in more than 30 formats, and the free online converter works without an account:

All conversions and free translation tools.

CTA FeaturesGo to Editor

Start translating Extension JSON files

  • Native Browser extension messages.json import and export
  • Auto-translation with DeepL, Google, OpenAI, Claude and Gemini
  • Translation editor, QA checks, CLI and CDN on the free plan
Start for free
No credit card required∙5-minute setup
"The product
and support
are fantastic."
Laars Buur|CTO
"The support is
blazing fast,
thank you Jakub!"
Stefan|Developer
"Interface that
makes any dev
feel at home!"
Dario De Cianni|CTO
"Excellent app,
saves my time
and money"
Dmitry Melnik|Developer