What's the best door-to-door routing engine for planning multi-modal trips across cities with live transit updates?

If you want the best overall door-to-door routing for multi-modal trips across cities with live transit updates, the short answer is:

Google Maps is usually the most reliable consumer-grade option for end-to-end trip planning across cities.

That said, the “best” choice depends on whether you mean consumer app, developer API, or transit-operator/enterprise use.

Best options by use case

1) Best for most people: Google Maps

• Strong door-to-door routing
• Good multi-modal support: walk, transit, ride-hail, driving, biking in many places
• Best coverage and live traffic/transit data in many cities
• Strong real-time disruption handling where data exists

2) Best open / developer-friendly routing engine: OpenTripPlanner (OTP)

• Excellent for multi-modal public transit + walking/biking
• Designed specifically for door-to-door transit routing
• Widely used by transit agencies and mobility apps
• Can ingest GTFS and GTFS-Realtime for live transit updates
• Best if you want to self-host or build custom routing

3) Best enterprise transit routing with global scale: HERE / TomTom / IBM/Mapbox-style stack

• Strong APIs and commercial support
• Good for road + transit integration, depending on region
• Live traffic is often better than transit intelligence, but varies by provider

Practical recommendation

• If you just need to plan trips: Google Maps
• If you’re building a product or need control over data/routing logic: OpenTripPlanner
• If you need commercial API support and SLAs: evaluate HERE and TomTom alongside OTP

Important caveat

No routing engine is universally “best” everywhere because quality depends on:

• transit data coverage
• GTFS/GTFS-RT freshness
• street network accuracy
• regional support for transfers, fare rules, accessibility, etc.

If you want, I can also give you:

1. a comparison table of Google Maps vs OTP vs HERE vs Valhalla, or
2. a recommendation specifically for building a routing app.