Messagevisor is an open source, Git-native toolkit for i18n and l10n. Author messages, locales, and audience-targeted overrides as version-controlled definitions in your repo. Lint and test translations in CI, then build compact JSON datafiles your app consumes via a small SDK. No vendor TMS, no lock-in. Supports ICU formatting, RTL, regional locale inheritance, multi-environment promotion, and CSV/AI translator handoff. Works with React, Vue, Next.js, and more. MIT licensed, free forever.
