GTFS Chat

Live app: https://sysdevrun.github.io/gtfs-sqljs-chatbot2/

A fully static, browser-only chatbot for any GTFS transit feed. Pick a feed (search, URL, or drag & drop a ZIP), it loads into an in-browser SQLite database (gtfs-sqljs in a Web Worker), and you chat with a Claude model that answers transit questions — stops, routes, next departures, realtime delays, alerts — by calling client-side tools that query that database.

No backend. Deployed on GitHub Pages. BYOK: you paste your own Anthropic API key; it is stored in localStorage and sent only to api.anthropic.com, directly from your browser.

How it works

• Feed selection — react-gtfs-selector with transport.data.gouv.fr and Mobility Database sources, plus direct URL and local ZIP drag & drop. Third-party URLs are wrapped with the SysDevRun CORS proxy.
• GTFS engine — gtfs-sqljs (v0.8, async adapter API) + sql.js running in a Web Worker via comlink, with an IndexedDB cache so reloading the same feed takes ~1 second.
• Stop search — a MiniSearch fuzzy/prefix index (diacritics-insensitive) built after feed load; the model resolves stop names through it and never guesses stop IDs.
• Agent loop — @anthropic-ai/sdk with dangerouslyAllowBrowser: true, streaming responses and client-side tool use (search_stops, get_stop_departures, get_trip_schedule, get_route_schedule, get_alerts, get_vehicle_positions, …). Departures/arrivals come from getTripSchedules(), which handles past-midnight times, timezones/DST, and GTFS-RT delay resolution.

Development

npm install
npm run dev        # local dev server
npm run typecheck  # tsc --noEmit
npm run build      # typecheck + production build to dist/
npm run preview    # serve the production build

Deployment

Pushes to main trigger .github/workflows/deploy.yml, which builds and deploys dist/ to GitHub Pages (repo Settings → Pages → Source: GitHub Actions). vite.config.ts uses base: './' so the site works under https://<owner>.github.io/<repo>/.

Security notes

• Your API key lives only in this browser's localStorage and is only ever sent to api.anthropic.com. Use a dedicated key with a spend limit.
• No raw HTML is rendered from model output (react-markdown without HTML plugins) and a CSP meta tag restricts scripts to the app bundle (plus wasm-unsafe-eval required by sql.js).