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Chrome · Firefox · Edge · Safari · Opera

AI localization for any browser extension

Upload your source messages.json, pick target languages, pay once, and download a ready-to-ship _locales ZIP.

Placeholder-safe translations
WebExtension messages.json compliant
Transparent pricing
messages.json
Source language (example)
{
  "appName": {
    "message": "My Extension",
    "description": "Name"
  },
  "welcomeMsg": {
    "message": "Hello, $USER$!",
    "placeholders": {
      "user": {
        "content": "$1"
      }
    }
  }
}
German (output)
{
  "appName": {
    "message": "Meine Erweiterung",
    "description": "Name"
  },
  "welcomeMsg": {
    "message": "Hallo, $USER$!",
    "placeholders": {
      "user": {
        "content": "$1"
      }
    }
  }
}
52 locales

How it works

Three simple steps to localize your WebExtension. Translations run after payment—we queue jobs and generate the ZIP in minutes.

01

Upload

Drop your source messages.json file. We parse it instantly and validate the WebExtension format.

02

Select languages & see price

Choose from 52 languages. See transparent pricing based on your file size before you pay.

03

Download ZIP

Pay once via Stripe. We generate all _locales/{lang}/messages.json files and bundle them into a ZIP.

Live pricing demo

Transparent pricing estimator

See exactly what you'll pay before uploading. Final quote is computed after upload based on string length and languages selected.

1. Upload file

Drop messages.json here

or click to browse

Chrome, Firefox, Edge, Opera & Safari. Max 500KB.

2. Select languages

|

3 of 55 languages selected

3. Your estimate

Languages selected3

Final price calculated after file upload on checkout page

One-time payment • No subscription

Built for developers

Purpose-built for WebExtension locale format. Not a generic translation tool.

WebExtension format aware

Built specifically for WebExtension messages.json structure with message, description, and placeholders support.

Placeholder protection

Preserves $PLACEHOLDER$ syntax exactly as-is. Your variables stay intact across all languages.

Description context

We read your description fields and use them as context hints for more accurate AI translations.

ZIP export ready

Download a ZIP with correct _locales/{lang}/messages.json folder structure. Drop it into your extension.

Parallel processing

All languages are translated simultaneously. Most jobs complete in under 5 minutes.

One-time payment

No subscriptions, no monthly fees. Pay once per job, download forever.

How WebExtension extension i18n works

WebExtensions store locale strings in _locales/{locale}/messages.json. Adding "default_locale" to manifest.json enables the i18n API. Chrome, Firefox, Edge, Opera, and Safari all use this same format — LocalePack handles the translation and correct folder structure for every browser in one order.

_locales/ folder structure
_locales/
├── en/
│   └── messages.json   ← default_locale
├── de/
│   └── messages.json
├── fr/
│   └── messages.json
└── ja/
    └── messages.json
messages.json
{
  "appName": {
    "message": "My Extension",
    "description": "Extension name"
  },
  "greeting": {
    "message": "Hello, $USER$!",
    "placeholders": {
      "user": { "content": "$1" }
    }
  }
}

Runtime API

chrome.i18n / browser.i18n

Example call

getMessage("key")

Required in manifest

"default_locale"

A complete _locales/ folder is required for your extension to display in users' languages across all browser extension stores. Each store reads the locale folder automatically.

messages.json format explained →

Why not just use generic tools?

General-purpose translation tools don't understand WebExtension format.

LocalePack
Manual translation
Generic TMS
Setup time2 minutesHours per language30+ minutes
Cost transparency
WebExtension format safety
Placeholder protection
Speed (52 languages)< 5 minWeeksHours
Best forAll WebExtension formatsSmall projectsEnterprise web apps

Success Cases

Real projects that used LocalePack to reach a global audience in up to 52 languages.

AstrologerAI AI astrology app localized into 52 languages

AstrologerAI: an AI astrology app localized into 52 languages

How the AstrologerAI app translated its entire experience into 52 languages with LocalePack — 6.3M tokens for $58.73 — to reach a worldwide audience in their own language.

DevToys.pro developer tools web app localized into 52 languages

DevToys.pro: 400% international traffic growth across 52 languages

How the DevToys.pro web app translated its entire UI into 52 languages with LocalePack — 5.8M tokens for $58.44 — and quadrupled its international organic traffic.

DevToys New Tab Chrome extension localized into 52 languages

DevToys New Tab: a Chrome extension localized UI + store listing in 52 languages

How the DevToys New Tab Chrome extension localized both its in-extension UI and its Chrome Web Store listing into 52 languages to reach a global audience.

The LocalePack site localized into 52 languages with LocalePack

LocalePack localized itself into 52 languages — with LocalePack

We used our own tool to translate the entire LocalePack site into 52 languages — 2.9M tokens for $27.37 — so developers worldwide find us in their own language.

View all success cases

Trusted by extension developers

“Saved me hours of tedious work. Uploaded my messages.json, got back perfect translations in the exact format I needed.”

Sarah K.

Indie dev, AdBlock extension

“Works for all my extensions — Chrome, Firefox, and Edge. One upload, all formats covered.”

Marcus T.

Extension maintainer

“Transparent pricing was the selling point. I knew exactly what I'd pay before uploading anything.”

Dev J.

Open source contributor

52

Locales supported

100%

Placeholder-safe output

ZIP

Ready to ship

Frequently asked questions

Everything you need to know about LocalePack.

Ready to ship your WebExtension globally?

Pay once - Download ZIP - Ship globally

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