GTFS Garage

A local browser for GTFS feeds. Open a feed and get tables whose IDs are clickable across files, a filter builder that never asks you to write SQL, and a map of the stops and route shapes.

Built for feeds that are too large or too cross-referenced to inspect in a spreadsheet: DuckDB queries the .txt files where they sit, so there is no import step and only the rows on screen are ever materialised.

• Follow an ID across files. Every foreign key (route_id, trip_id, shape_id, stop_id, service_id, …) is a link to the referenced row, and a table's own id column offers the reverse direction — from a route straight to the trips that use it. Links to files a feed does not contain are not shown.
• Open a feed from anywhere. A .zip or an extracted folder, chosen from the page or dropped onto it, a local path, or a URL the tool downloads.
• Filter without SQL. Pick a column, an operator (is, is not, contains, is one of, is empty, is not empty) and a value. Columns GTFS defines as enumerations (continuous_pickup, route_type, wheelchair_boarding, …) offer a picklist of the values actually present, with counts.
• See it on a map. Stops and route shapes render from the feed's own shapes.txt, coloured by its route_color, and a flex feed's on-demand zones are drawn from locations.geojson. Per-row buttons highlight a particular stop, shape, route or zone. The map can be turned off, and while it is off none of its data is fetched.
• Open a large feed. A multi-gigabyte feed is converted once to a columnar store at load, so queries stay in milliseconds instead of re-reading gigabytes of CSV, and the map streams in progressively rather than arriving in one piece that no browser can hold. Every stop, route and shape is drawn at any size. Once shapes.txt passes 600,000 rows the map's lines start losing intermediate points in proportion, and the map says so; tables, filters and counts behave identically at every size.
• See what it cost. Every load reports its own timings and sizes: the download or upload, the unzip, the conversion, and per file the bytes on disk, the rows, and the time spent reading the header versus counting the rows. The header carries a one-line summary that opens into the full breakdown, largest file first.
• Go back. Every table switch, filter change and page turn is a history entry, so Back — in the app or the browser — returns to the previous view with its filters intact. The URL describes the view, so it can be reloaded or shared.

Requirements

Python 3.11 or newer. Released packages ship with the interface already built, so installing does not require Node. Node 22 or newer is needed only to work from a source checkout, where the frontend has to be built once.

Installation & Usage

pip install gtfs-garage
gtfs-garage path/to/feed.zip

That opens http://127.0.0.1:8811. The argument accepts a .zip or an already-extracted folder, and zips that wrap their .txt files in a subfolder work too. Omit it to pick a feed in the browser instead — drag a zip in, or give a local path or a URL for the tool to download.

gtfs-garage [--host HOST] [--port PORT] [--basemap NAME|URL] [--no-browser]
            [--no-parquet] [--version] [feed]

At load the feed is rewritten once as Parquet and the CSVs it came from are released. On a 4.5 GB feed that costs about six seconds and pays for itself immediately: counts and filters go from seconds to milliseconds, and the feed occupies roughly a twentieth of the disk. --no-parquet keeps the original behaviour of reading the CSVs where they sit.

The map backdrop is configurable with --basemap or $GTFS_GARAGE_BASEMAP: openfreemap (default), esri, osm, carto, none, or any raster tile template or vector style URL. All presets except carto work without an API key.

The Python API is usable on its own, without the server:

from gtfs_garage.core import GtfsFeed, query_table

feed = GtfsFeed("path/to/feed.zip")
page = query_table(feed, "trips", [{"column": "route_id", "op": "eq", "value": "R1"}])

Local development

One script sets up the Python environment, installs both sets of dependencies, builds the interface and starts the tool. It is safe to re-run and works from a fresh clone:

scripts/run-app.sh path/to/feed.zip

While working on the code, use hot-reload mode instead. Frontend edits appear immediately and Python edits restart the API, so nothing is rebuilt to see a change:

scripts/run-app.sh path/to/feed.zip --dev

--help lists the options (--port, --basemap, --skip-install, --no-browser).

The frontend build output is not in version control, so a checkout has none until it is built. Without it the API still runs and the page explains what to do, rather than failing obscurely. The individual frontend commands live in web/: yarn dev, yarn build, yarn typecheck, yarn test.

Linter

scripts/lint-tests.sh   # check
scripts/lint-write.sh   # fix

flake8 and black at a line length of 120, matching MobilityData's other Python components. pre-commit install wires the check into commits.

Tests

scripts/tests.sh

pytest with branch coverage, which must stay at or above 80%. This includes the performance guards in tests/test_performance_guards.py, which assert the structural properties behind past regressions - how often a file is scanned, what a map feature carries, whether a handler blocks the event loop.

One guard needs a real browser and is excluded from that run, because peak memory is the one thing no server-side test can see:

pip install -e ".[dev,perf]" && playwright install chromium
(cd web && yarn build)
pytest -m browser

scripts/benchmark.sh measures a generated feed: payload sizes, feature and vertex counts, and the time each phase takes. It reports rather than asserts.

On a pull request, CI runs it twice on the same runner - once on the branch, once on its merge base - and posts the difference as a comment, so a number is judged against main rather than read in isolation. Exact metrics like payload bytes are flagged when they move; timings are shown but vary with the runner.

Documentation

• docs/ARCHITECTURE.md — the stack, the layers and why they are split the way they are, including which pieces are built to be used from outside this repository.

License

Apache 2.0. See LICENSE.