Fairspec Cardealer

Updated May 9, 2026

Fairspec Cardealer is a reference Fairspec extension that captures the data model of a car dealership — vehicles, listings, dealers, and transactions. It is published as a versioned profile alongside its specification and validation tests, and serves as a concrete example of what a fully-formed Fairspec extension looks like.

Why look at it

• End-to-end example. It demonstrates the full lifecycle of an extension — from JSON Schema profile to documentation to release — built on top of the Fairspec Extension Template.
• Domain-specific properties. Shows how to add custom fields (vehicle make, model, mileage, listing price) while remaining structurally compatible with the base Fairspec Dataset schema.
• Composition with base profiles. Illustrates the allOf pattern used to combine the base Fairspec dataset profile with a domain mixin.

Use Cardealer as a starting point when designing your own extension, or as a teaching example when explaining the extension mechanism to new contributors.