Locale file checkers compared

Six open-source tools that check translation files. They overlap less than their names suggest: some read only JSON, some check your source code rather than the translations, one is built for Rails. Every value below comes from the project’s own README, source code or registry page.

We make Shipi18n, one of the six. Last verified 4 October 2026.

	Shipi18n	i18n-check	i18n-tasks	i18next-cli	i18n-validate	LocaleGuard
Placeholder parity between locales	Yes — ICU, {{i18next}}, %{rails}, %(python)s, printf, %@	Yes — ICU and i18next messages parsed and compared	Yes, in health by default — Ruby %{name} syntax only	No — lint compares t() params with the primary locale, not locales with each other	Yes — {x}, {{x}}, %s	Yes — {x} and {{x}}; not a full ICU validator (its README)
Plural forms per language (CLDR)	ICU plurals: yes. i18next _one/_other keys: compared with the source only	Only branches present in both files	Yes, using rails-i18n plural rules	Yes — status uses each language’s plural categories	Yes — CLDR v44 plural requirements	vue-i18n a \| b only
Locale formats	JSON, YAML/Rails, ARB, .xcstrings, Android XML, PO, XLIFF	JSON, YAML	YAML, JSON (Ruby i18n gem projects)	JSON, JSON5, YAML, TS/JS (i18next)	32 formats claimed, incl. ARB, .xcstrings, Android, PO, XLIFF, RESX, TMX	JSON, YAML, XLIFF, PO
Scans your source code	No	Yes — unused/undefined keys (react-intl, i18next, next-intl)	Yes — Ruby/ERB AST scanner, regex for others	Yes — hardcoded strings, interpolation params, key extraction	No	Yes — hardcoded strings, unused/undefined keys (React, Vue, Angular)
CI and output	GitHub Action, SARIF, JSON, Docker, pre-commit	Exit code; text output; no Action	Exit code; table, YAML, JSON output; no Action	Exit code (status, lint, extract --ci); no Action	Terminal, JSON, JUnit; no Action, no SARIF	GitHub Action, SARIF, Markdown, JSON
Adoption (week of 25 Sep 2026)	≈560 npm downloads/week (CLI); new	≈306,000 npm downloads/week	33.8M total RubyGems downloads; 2,100+ stars	≈1,010,000 npm downloads/week	≈8 npm downloads/week; npm still at 0.1.0	≈4 npm downloads/week
License	Apache-2.0	MIT	MIT	MIT	MIT (Rust; from i18nagent.ai)	Apache-2.0

Which one fits

Rails app: start with i18n-tasks — it is the native tool and its health command already checks %{name} parity.
i18next web app: i18next-cli finds hardcoded strings and missing keys; it does not compare placeholders between languages, so pair it with a locale checker.
react-intl / next-intl, JSON only: i18n-check is the widely used choice and also finds unused keys.
Mobile or mixed formats (ARB, .xcstrings, Android, gettext, XLIFF) or PR annotations: Shipi18n or i18n-validate; only Shipi18n ships a GitHub Action with SARIF for those formats.

Code scanners and locale checkers answer different questions, so pairing one of each is common. Closer looks: Shipi18n vs i18n-check, vs Lingo.dev.

What the check prints

$ npx @shipi18n/cli check ./locales -s en
🔎 shipi18n check — flat layout, source 'en', 2 target language(s)

✗ de  coverage 100.0%  2 error(s), 1 warning(s)
    error  welcome  placeholder-missing — dropped {name}
           fix: restore {name} exactly as written in the source
    error  checkout  placeholder-missing — dropped {amount}
           fix: rename {betrag} to {amount}
    warning  checkout  placeholder-added — unexpected {betrag}
✓ pl  coverage 100.0%  0 error(s), 0 warning(s)

✗ check failed: 2 error(s)

No account and no API key. Exit code 1 fails the CI job; the GitHub Action also annotates the PR lines. Quick start

Last verified 4 October 2026 (2026-10-04) against these primary sources. Prices and features change; if something here is out of date, open an issue.