GTFS, or the General Transit Feed Specification, defines a common data format for public transportation schedules and associated geographic information. GTFS contains only static or scheduled information about public transport services, and is sometimes known as GTFS Static or GTFS Schedule to distinguish it from the GTFS Realtime extension, which defines how information on the realtime status of services can be shared.

What was to become GTFS started out as a side project of Google employee Chris Harrelson in 2005, who "monkeyed around with ways to incorporate transit data into Google Maps when he heard from Tim and Bibiana McHugh, married IT managers at TriMet, the transit agency for Portland, Oregon". McHugh is cited with being frustrated about finding transit directions in unfamiliar cities, while popular mapping services were already offering easy-to-use driving directions at the time.

Bibiana and Tim McHugh eventually got into contact with Google and provided the company with CSV exports of TriMet's schedule data. In December 2005, Portland became the first city to be featured in the first version of Google's "Transit Trip Planner". In September 2006, five more US cities were added to the Google Transit Trip Planner, and the data format released as the Google Transit Feed Specification.

In the United States, there had not been any standard for public transit timetables prior to the advent of GTFS, not even a de facto standard. According to long-time BART website manager Timothy Moore, before the advent of GTFS, BART had to provide different data consumers with different formats, making a standardized transit format very desirable. The publicly and freely available format specification, as well as the availability of GTFS schedules, quickly made developers base their transit-related software on the format. This resulted in "hundreds of useful and popular transit applications" as well as catalogues listing available GTFS feeds. Due to the common data format those applications adhere to, solutions do not need to be custom-tailored to one transit operator, but can easily be extended to any region where a GTFS feed is available.

Due to the wide use of the format, the "Google" part of the original name was seen as a misnomer "that makes some potential users shy away from adopting GTFS". As a consequence, it was proposed to change the name of the specification to General Transit Feed Specification in 2009.

GTFS is typically used to supply data on public transit for use in multi-modal journey planner applications. In most cases, GTFS is combined with a detailed representation of the street/pedestrian network to allow routing to take place from point to point rather than just between stops. This data is often extended using GTFS-Realtime to factor delays, cancellations, and modified trips into realtime journey planning queries. OpenTripPlanner is open-source software that can do journey planning with a combination of GTFS and OpenStreetMap data. Other general purpose applications exist such as the ArcMap Network Analyst extension which can incorporate GTFS for transit routing.

GTFS was originally designed for use in Google Transit, an online multi-modal journey planning application.

GTFS is often used in research on transit accessibility where it is typically used to estimate travel times by transit from one point to many other points at different times of day. Studies however have called such applications into question due to their reliance on schedules alone without accounting for reliability issues and regular schedule non-adherence.