GPX vs FIT vs GeoJSON

Three file formats dominate the world of GPS and fitness data: GPX, FIT, and GeoJSON. Each was designed for a different purpose, by different organizations, with different technical trade-offs. This guide provides an in-depth comparison to help you understand when and why each format is used.

GPX — GPS Exchange Format

History

GPX was created by TopoGrafix, a company founded by Dan Foster in Stow, Massachusetts. Development began in late 2001 through discussions among GPS software developers who wanted an open, device-independent format to replace the many proprietary GPS data formats in use at the time.

• GPX 1.0 was released on 1 March 2002
• GPX 1.1 was released on 9 August 2004 and remains the current version
• The specification is public domain, meaning anyone can implement it freely

Technical Details

GPX is an XML-based format, meaning files are plain text and human-readable. Key characteristics include:

• Schema: http://www.topografix.com/GPX/1/1
• Root element: <gpx> with required version and creator attributes
• Three core data types:
  • Waypoints (<wpt>) — individual named locations
  • Routes (<rte>) — ordered sequences of turn points for navigation
  • Tracks (<trk>) — recorded GPS traces, containing segments (<trkseg>) of track points (<trkpt>)
• Each point stores latitude and longitude as XML attributes; elevation and time are child elements
• A <metadata> element can hold name, description, author, copyright, links, keywords, and creation time
• Extensibility via <extensions> elements (e.g., Garmin's TrackPointExtension for heart rate, cadence, power, and temperature)
• Coordinates use decimal degrees in the WGS84 datum

References

• GPX specification at TopoGrafix
• GPX 1.1 schema documentation
• GPX on Wikipedia

FIT — Flexible and Interoperable Data Transfer

History

The FIT protocol was developed by Dynastream Innovations, a technology company based in Cochrane, Alberta, Canada. Dynastream created the ANT wireless protocol in 2003 and the ANT+ interoperability framework in 2004, both widely used for connecting fitness sensors to devices.

• Garmin acquired Dynastream in December 2006 for approximately $36 million
• The FIT format emerged around 2009–2010 as a purpose-built format for fitness device data storage and transfer
• FIT replaced Garmin's earlier TCX (Training Center XML) format as the preferred activity recording format
• Dynastream was later renamed to Garmin Canada Inc. in 2018
• The FIT SDK is available in 8 programming languages: C, C++, C#, Java, JavaScript, Objective-C, Python, and Swift

Technical Details

FIT is a binary format, meaning files are compact and machine-readable but not human-readable. Key characteristics include:

• Message-based protocol: a FIT file contains a sequence of data messages, each with a local message type, fields, and values
• Key message types: file_id, activity, session, lap, record, device_info, sport, workout
• Timestamps use the FIT epoch (31 December 1989, 00:00:00 UTC) as their base
• Coordinates are stored as semicircles (180 / 2³¹ degrees per semicircle), an integer representation that avoids floating-point rounding
• Native sensor support: heart rate, power, cadence, temperature, speed, distance, altitude, GPS coordinates, training zones, workout steps, and device info are all first-class fields
• A Profile.xlsx file defines all standard messages and field types in the SDK
• File types: Activity, Course, Workout, Sport, Settings, Goals, and more
• CRC integrity checking ensures data has not been corrupted
• Forward-compatible: older parsers can safely skip unknown messages, so the format evolves without breaking existing software

References

• FIT SDK overview at Garmin
• FIT protocol documentation

GeoJSON

History

GeoJSON was created by a working group of six developers: Howard Butler, Martin Daly, Allan Doyle, Sean Gillies, Tim Schaub, and Christopher Schmidt. The format draws on concepts from the OpenGIS Simple Features specification.

• Working group discussions began in March 2007
• GeoJSON 1.0 was published on 16 June 2008 at geojson.org
• The IETF Geographic JSON working group was formed in October 2015 to standardize the format
• Published as RFC 7946 in August 2016 (IETF Proposed Standard), superseding the 2008 specification

Technical Details

GeoJSON is a JSON-based format, making it human-readable and natively compatible with JavaScript and web applications. Key characteristics include:

• Seven geometry types: Point, MultiPoint, LineString, MultiLineString, Polygon, MultiPolygon, GeometryCollection
• A Feature object wraps a geometry with a properties object for arbitrary metadata
• A FeatureCollection groups multiple Features into a single object
• Coordinate order: longitude first, then latitude — the opposite of GPX's latitude, longitude order
• An optional third coordinate value represents altitude
• WGS84 coordinate reference system is mandated by RFC 7946
• MIME type: application/geo+json (per RFC 7946) or application/json
• Encoding: UTF-8
• The properties object can hold any JSON key-value pairs — there is no predefined schema
• No native concept of time, tracks, routes, or sensor data — these must be encoded as custom properties

References

• GeoJSON specification
• RFC 7946 — The GeoJSON Format
• GeoJSON on Wikipedia

Comparison Table

Where Each Format Is Used

GPX

• Route planning: Komoot, Ride with GPS, AllTrails
• GPS devices: Garmin, Wahoo, Coros (import and export)
• Sharing: OpenStreetMap, cycling forums, hiking communities
• Navigation: most GPS devices accept GPX course files
• Geocaching: the standard format for cache locations and logs

FIT

• Garmin devices: Edge, Fenix, Forerunner, Venu (native recording format)
• Other devices: Wahoo, Bryton, Stages (also record in FIT)
• Analysis platforms: Strava, TrainingPeaks, Today's Plan, GoldenCheetah
• Virtual training: Zwift
• Data sync: Garmin Connect

GeoJSON

• Web mapping: Leaflet, Mapbox GL, Google Maps API, OpenLayers
• GIS software: QGIS, ArcGIS
• Databases: PostGIS, MongoDB geospatial queries
• Code platforms: GitHub renders GeoJSON files natively on a map
• APIs: many location-based services use GeoJSON as their data interchange format

Which Format Should You Use?

• Sharing a route for navigation — use GPX. It is nearly universally supported by GPS devices and route-planning tools.
• Recording an activity with sensor data — use FIT. It natively supports heart rate, power, cadence, laps, and all the metrics fitness platforms expect.
• Displaying data on a web map or in a GIS tool — use GeoJSON. It integrates directly with JavaScript mapping libraries and spatial databases.
• Maximum compatibility — use GPX. Almost every GPS application, device, and platform can read GPX files.
• Smallest file size — use FIT. Its compact binary encoding produces files significantly smaller than the equivalent XML or JSON.
• Easiest to work with programmatically — use GeoJSON. It can be parsed natively in any language with a JSON parser, and its structure maps cleanly to objects and arrays.

References

• GPX specification — TopoGrafix
• GPX 1.1 schema documentation
• GPX on Wikipedia
• FIT SDK overview — Garmin
• FIT protocol documentation — Garmin
• Garmin acquires Dynastream Innovations — BioSpace
• GeoJSON specification
• RFC 7946 — The GeoJSON Format
• GeoJSON on Wikipedia
• GeoJSON at the Library of Congress