A Curiosity 175 production
Trackser Live fetches, merges, cleanses and enriches TfL's live train data for all 11 London Underground lines — then serves compact, ready-to-read snapshots from the edge. The app never touches TfL directly.
What is Trackser Live
Rather than having every device consume raw TfL feeds directly, Trackser Live does the work once, centrally. It ingests TfL's TrackerNet feeds — the same granular source used in real-time train control — merges the sightings, cleanses destinations, infers direction, detects stalls, and folds in timetable and journey context. The result is a faster, lighter and more accurate experience for everyone using the Trackser app.
It's built on Cloudflare Workers and R2, with one Durable Object per line owning that line's state. Snapshots are rebuilt continuously and served compressed from the edge.
What it does
Every snapshot is cleaned up and augmented server-side, so clients receive meaning, not raw feed noise.
Real-time train positions for all 11 lines, merged from many station sightings into one record per train.
Every train is resolved to a direction and a next physical stop, anchored to its true reported location.
Trains that stop moving are flagged, so downstream ETAs and boards don't quietly go stale.
Messy feed destinations and disruption text are normalised into clean, human-readable values.
Booked stopping patterns and platforms — including the Metropolitan line's many branches — spliced onto live data.
Every snapshot is archived: full resolution for 14 days, downsampled beyond, with per-day journey records.
Part of the Trackser family
Trackser Live is infrastructure — the products below are what it feeds.
The Trackser app on Android, iOS and web — live maps, departures, unit numbers and service status for the whole Underground.
Visit Trackser →
Pass unlocks the archive Trackser Live keeps — unlimited history, the Replayer, and full unit tracking.
Explore Pass →
Pulse reads the live picture Trackser Live produces to detect disruption the moment it starts.
Explore Pulse →For developers
The developer portal covers the API surface, the ingestion-to-edge architecture, and the upstream data sources — all kept in step with the running system. The status page reports pipeline health per line, backed by independent uptime monitoring.
API access is currently internal. The API serves the Trackser app exclusively today. If you have a project that would benefit from this data, we'd genuinely consider it — get in touch with your use case.
Data attribution. Trackser Live processes data from Transport for London Open Data under the TfL Open Data Licence. It is not affiliated with or endorsed by TfL. Train data is provided for information only and must not be used for safety-critical decisions.