glot

AI-native localization for SaaS. Git is the source of truth, your coding agent is the interface, and every LLM output goes through deterministic code before it touches your catalogs.

glot is a Rust CLI + MCP server + optional API/dashboard. It works with the i18n library you already use (next-intl, i18next, FormatJS…) and ships no runtime.

Why glot (vs Lokalise, Crowdin, Lingo.dev)

Related MCP server: i1n

Install

npx glot-i18n init                                                              # no install: npm fetches the binary
npm i -g glot-i18n                                                              # `glot` on PATH (macOS, Linux, Windows)
brew install mattjeff/glot/glot                                                 # Homebrew (macOS, Linux)
curl -fsSL https://raw.githubusercontent.com/MattJeff/glot/main/integrations/install.sh | sh   # ~/.local/bin
cargo install --git https://github.com/MattJeff/glot glot-cli                   # from source

Every prebuilt binary comes from the GitHub release and is checked against its SHA-256 before install (pinned in the npm package and the formula; release digests for install.sh).

Quickstart

glot init                          # detects your stack, writes glot.toml + agent rules
claude mcp add glot -- glot mcp    # give Claude Code live i18n context
export ANTHROPIC_API_KEY=...
glot translate                     # translates missing/stale strings, validated
glot check                         # CI-friendly: --format text|json|sarif|github

LLM providers

The system prompt (rules + glossary) is a cached prefix, so repeated batches pay ~10 % of its price. glot translate --batch sends the first pass through Anthropic's Message Batches API (-50 %, asynchronous, resumable).

Other commands: glot status, glot extract (hardcoded strings, missing/unused keys), glot set <locale> <key> "<value>", glot glossary, glot push|pull.

GitHub Action

on: pull_request
permissions: { contents: write, pull-requests: write }
jobs:
  i18n:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          repository: ${{ github.event.pull_request.head.repo.full_name }}
          ref: ${{ github.head_ref }}
      - uses: MattJeff/glot/action@v0
        with:
          # Fork PRs get no secrets: only check them, translate on same-repo branches.
          command: ${{ github.event.pull_request.head.repo.full_name == github.repository && 'both' || 'check' }}
          anthropic-api-key: ${{ secrets.ANTHROPIC_API_KEY }}

It validates catalogs (inline annotations), translates the delta, commits catalogs + glot.lock to the PR branch and keeps one PR comment up to date with coverage, issues and cost. See action/action.yml.

Visual QA

cd packages/visual-qa && pnpm install && pnpm exec playwright install chromium
node src/cli.ts --base-url http://localhost:3100 --routes /,/login --locales fr,de,ja,ar --suggest

Writes .glot/visual-qa/report.{json,md} and screenshots; exits 1 on overflow (--fail-on). report.md is ready to post as a PR comment. Add data-glot-key="auth.login.cta" to elements to get ready-to-run glot set fixes.

Task parity (glot parity)

Users and agents complete fewer tasks in non-English UIs. glot parity measures it for your app: an agent (Claude Sonnet 5.5, screenshot + reduced accessibility tree, click/type/select/scroll) gets each goal in the tested language (translated once, cached in .glot/parity/goals.json) and tries to complete it in every locale.

# glot.tasks.yaml — success conditions use catalog KEYS, so they hold in every language
- id: send_reminder
  goal: Invoice INV-1042 is overdue. Send the customer a payment reminder.
  start: /invoices
  success: { text_visible_key: invoice_actions.reminder_sent }   # and/or url_matches, selector
  script:                                                        # only for --provider mock
    - click: { selector: "a[href='/invoices/inv_1042']" }
    - click: invoice_actions.send_reminder_button               # found by its translated label

cd packages/agent-qa && pnpm install && cd -
glot parity --base-url http://localhost:3000 --locales en,fr,de,ja,ar [--url-pattern "{route}?lang={locale}"] [--locale-cookie NEXT_LOCALE] [--min-parity 90]
glot parity --provider mock      # scripted, deterministic, no tokens (CI)

Writes .glot/parity/report.{md,json} and a screenshot per step: a task × locale matrix (success, steps, time), a parity score per locale (share of the tasks the source locale completes), and findings tied to keys — truncated label, control not found, ambiguous label, broken RTL, untranslated text — with a fix (glot set fr invoice_actions.send_reminder_button "Relancer" when the agent looked for "Relancer"). Run it against a production build: dev servers recompile mid-run. The report stays local (no upload endpoint); post report.md as a PR comment. Example tasks: packages/agent-qa/examples/demo-saas.tasks.yaml.

Use with AI agents

• Claude Code: claude plugin marketplace add MattJeff/glot && claude plugin install glot@glot adds a glot skill (Claude uses it whenever you ask for a multilingual app), /glot:i18nize, /glot:translate and the MCP server. MCP only: claude mcp add glot -- npx -y glot-i18n mcp.

• Cursor / Windsurf / Codex: drop-in rules in integrations/agents (.mdc, Windsurf rule, AGENTS.md); MCP command npx -y glot-i18n mcp (stdio, run inside a project with glot.toml). Listed in the official MCP registry as io.github.MattJeff/glot.

• Lovable, Bolt, v0, Replit: paste the knowledge snippet so generated code is i18n-ready, then Translate this app: one workflow run does init + i18nize + translate and opens a PR.

Show your coverage with a translated by glot · N languages · X% badge. All integrations: integrations/.

Demo

examples/demo-saas is "Acme Invoices", a small Next.js SaaS with every string hardcoded in English (plurals by concatenation, copy in config objects, fixed-width buttons, ambiguous "Save"/"Archive" labels). examples/demo.sh takes a throwaway copy from hardcoded English to validated catalogs, with commentary at each step:

examples/demo.sh                                       # mock LLM, no key needed
DEMO_PAUSE=1 examples/demo.sh                          # pause between steps for a live demo
GLOT_REAL=1 ANTHROPIC_API_KEY=... examples/demo.sh     # real translations
KEEP=1 examples/demo.sh                                # keep the copy, then `pnpm install && pnpm dev` (port 3200)

Steps: init → extract (117 hardcoded strings) → i18nize (24 files rewritten to next-intl, 132 keys) → minimal next-intl wiring + next dev → translate --visual → check → fit (German overflow fixed in the running app) → review → glossary mine. NO_APP=1 skips the dev server (and thus --visual/fit). Commands missing from your build are skipped with a notice.

Architecture

Rust workspace (crates/core, extract, llm, mcp, cli, server), Next.js dashboard in web/, Playwright QA in packages/visual-qa, GitHub Action in action/. Details, file formats and the HTTP API: ARCHITECTURE.md.

Local development

docker compose up -d postgres      # postgres://glot:glot@localhost:5433/glot
cargo run -p glot-server           # API on :8790
cd web && pnpm install && pnpm dev # dashboard on :3100

Tests: cargo test --workspace (needs DATABASE_URL), cd web && pnpm lint && pnpm build, cd packages/visual-qa && pnpm test, cd packages/agent-qa && pnpm test.

Docker (full stack)

GLOT_SECRET_KEY=$(openssl rand -hex 32) docker compose --profile full up -d --build --wait
curl localhost:8790/healthz                # ok (migrations run at startup)
open http://localhost:3100                 # dashboard; /api and /cdn are proxied to the server
docker compose --profile full down         # add -v to drop the database volume

Host ports default to 5433 / 8790 / 3100; override with GLOT_PG_PORT, GLOT_API_PORT, GLOT_WEB_PORT (set GLOT_WEB_ORIGIN to the web URL if you change GLOT_WEB_PORT). The web image bakes the API URL into the Next build (rewrites are resolved at build time), so changing GLOT_API_URL means rebuilding web. Cold build: ~7 min server (mostly the Rust image pull, ~1.5 min compile), ~2 min web; images ~170 MB (server) and ~440 MB (web).

Dogfooding

The dashboard in web/ is translated by glot itself. Any PR touching web/messages/en.json runs dogfood.yml, which builds the CLI from the PR and runs our own action in web/ to translate, validate, commit and comment.

License

MIT © 2026 glot contributors