Schema Commons

A common schema for APIs, distilled from what providers already publish. Not a new standard written from scratch, but the vocabulary the market already shares, measured from the OpenAPI that providers publish about themselves.

For each domain we read the OpenAPI of the providers tagged with it in APIs.io, counting only specs a provider published itself and each company once. A property is core when at least half of the providers with a readable schema declare it, and extended at a fifth. Every context publishes a common OpenAPI, JSON Schema in which every property carries the share of providers that declare it, and a crosswalk from the common names to each provider's own. The naming conventions are measured too, and published as an OpenLint ruleset.

Where a standard already owns the shape, the commons does not re-derive it. A reference context publishes the standard's own objects unchanged and measures who implements them. Contexts measured against a standard (FHIR, schema.org, OCPI, CloudEvents and others) carry an OpenAPI Overlay that maps each common property to the standard's field.

The hub: method, tooling and registry · The full report · Standards registry

Reference contexts

Bounded contexts

Everything is draft (0.1.0-draft) until a context meets the lock criteria in the hub; the first 1.0.0 releases follow the next re-measure. A share is the fraction of providers that declare a property in their published OpenAPI, not a judgement of how well they populate it, and a crosswalk is a mapping, not a grade. Generated 2026-11-11.