Transit Land - Transitland brings together many sources of transit data to build a directory of operators and feeds that can be edited by transit enthusiasts and developers.
Transit Feeds - An extensive archive of public transit data for software developers, transit agencies and more.
Google Public Feeds - This is a list of transit schedule data published by transit agencies and operators in GTFS format for developers to use.
Google Transit Feed - A Python library for reading, validating, and writing transit schedule information in the GTFS format.
Node-GTFS - node-GTFS loads transit data in GTFS format, unzips it and stores it to a MongoDB database.
gtfs-utils – JavaScript utilities to process GTFS data sets (e.g., "flattening" calendar.txt & calendar_dates.txt, computing arrival/departure times of trips).
gtfs-realtime-bindings - Language bindings generated from the GTFS-realtime protocol buffer spec for popular languages.
GTFS-viz - Converts a GTFS dataset into a SQLite DB + GeoJSONs / KMLs.
onebusaway-gtfs-modules - A Java-based library for reading, writing, and transforming public transit data in the GTFS format, including database support.
GTFS Ruby - A Ruby wrapper for the General Transit Feed Specification.
GTFS Importer - Import GTFS data to SQLite for use in iOS and Android apps.
GTFSDB - Python code that will load GTFS data into a relational database, and SQLAlchemy ORM bindings to the GTFS tables in the gtfsdb.
gtfs osm sync - Synchronizes public transportation data in GTFS format with OpenStreetMap.org.
GTFS as a Django app - Django app to import and export General Transit Feed Specification (GTFS).
GeoTrellis Transit - API and libraries for generating travelsheds from OSM & GTFS data.
GTFS Feed Parser - .Net/Mono implementation of a General Transit Feed Specification (GTFS) feed parser.
FastGtfs - Rust library to parse and merge GTFS data, designed for embedded systems. It converts the txt format in a binary one, faster to parse. It also provides a navigator (given start and destination point gives several results), and enables the creation a network simulation in real time.
gtfsutils - GTFS command-line tool and Python GTFS utility library
Data Viewers
GTFS to HTML - Build HTML timetables from GTFS transit data.
GTFS Visualizer - Library responsible for generating HTML data based on the GTFS format.
LiveMap - Real-time visualization of public transportation based on parsed GTFS data sets.
gtfs-rt-inspector - Web app to inspect & analyze any GTFS Realtime feed.
Multimodal Trip Planning
Open Trip Planner - OpenTripPlanner provides a range of passenger information and transportation network analysis features using our infrastructure for finding itineraries combining transit, pedestrian, bike, and car segments.