i18next JSON files are code-adjacent. A translated string can be linguistically fine and still break a UI if it drops {{count}}, removes a nested key, or leaves the file as invalid JSON.

A small automated check gives reviewers a stable baseline before they spend time judging tone, context, and product language.

This job uses the free JSON Translate Check Action to compare translated files against the source locale on every pull request:

name: Locale checks

on:
  pull_request:

jobs:
  json-locales:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Validate translated JSON locale files
        uses: OlsOls2/json-translate-check-action@v1
        with:
          source: locales/en.json
          targets: locales/fr.json,locales/de.json

If your team prefers local checks before pushing, add a script to package.json:

"scripts": {
  "check:locales": "json-translate-check --source locales/en.json --target locales/fr.json,locales/de.json"
}

Developers can then run npm run check:locales before opening a pull request.

Automation should handle the shape of the file. Humans should still review the meaning of the translation, especially:

• Checkout, billing, and upgrade screens.
• Authentication and account recovery messages.
• Errors, empty states, and destructive-action confirmations.
• Strings with plural logic, interpolation, and product-specific terminology.

Use JSON Translate for the translation step, then use @json-translate/check as a guardrail before merge. That gives you fast draft translations plus repeatable structural QA.