APIvaries

APIvaries is an open data project and reference resource that catalogs the differences among application programming interfaces (APIs) produced by different vendors and platforms. The project aims to illuminate how APIs vary in structure, semantics, and behavior so developers can compare, migrate, or compose services across ecosystems.

Scope and features: APIvaries collects metadata about APIs including endpoints, HTTP methods, URL templates, parameter schemas, request and response payloads, authentication schemes, error handling, versioning, deprecation notices, and rate limits. It provides standardized mappings between similar endpoints across providers, annotations of compatibility gaps, and tools for side-by-side diffs and semantic similarity scoring. The data model supports cross-version alignment, feature-based comparisons, and export formats suitable for tooling.

Data model and standards: Core entities include API, Version, Endpoint (or Operation), Parameter, Response, Error, and Authentication. An API has Versions; Versions own Endpoints; Endpoints define Parameters and Responses. APIvaries strives to align with open API specifications such as OpenAPI, RAML, and AsyncAPI when available, and accommodates custom schemas when official specs are missing.

Usage: Software developers, system integrators, and technical researchers use APIvaries to assess compatibility for cross-API integration, plan adapters or middleware, and study trends in the API economy. The platform offers REST and GraphQL access, a web UI for browsing, programmatic search, and downloadable data or citations for research and documentation.

Governance and licensing: APIvaries is an open-source project with community governance. Contributions are managed via a public repository, and data contributions respect permissive licenses to encourage reuse while protecting source integrity. Data provenance and versioning are tracked to maintain reproducibility.

History and status: Conceived in the early 2020s by a coalition of developers and researchers, APIvaries released its first public dataset in 2023. It continues to add providers and schemas, with ongoing work on improved matching algorithms and interoperability guidelines.