Plan your business evaluation.

What should an API evaluation brief define?

Choose one API change, the contract baseline, and the repositories your organization authorizes. Record the language and transport, expected application behavior, required checks, and success criteria. Start with shadow-mode reporting before considering repository writes.

The brief is planning input. It is not an automatic support verdict, a commercial agreement, or a permission grant. Use the local download to review the scope with your team, then plan a business evaluation.

Online OpenAPI and JSON Schema compatibility checks

Use this free API compatibility checker to understand how a contract change affects existing integrations. Replay a captured OpenAPI finding from OpenAI or Sentry, inspect its classification rule, or compare a pair of JSON Schemas. The examples run without an account or repository access. Each result separates contract evidence from the question of whether your application uses the affected operation.

• Request narrowing

  The revised request schema must accept the inputs existing callers could send. Increasing a minimum, decreasing a maximum, or tightening a string constraint can reject previously valid requests. Check the affected field and the acceptance direction.

• Enum value removal

  Removing a request enum value leaves callers using that value outside the new contract. Inspect where the value is selected before choosing an alternative; the specification finding does not invent a replacement for your application.

  Recorded rule: request.enum_removed

• Required request field addition

  Adding a required property, or making an optional request field required, can reject older payloads that omit it. A compatible migration needs an appropriate application value, not simply a placeholder added to satisfy the schema.

• Response widening

  Existing consumers must handle the outputs allowed by the revised response. A field becoming optional or nullable, a new enum value, or a broader type can invalidate assumptions in parsing, branching, and typed response handling.

  Recorded rule: response.now_optional_or_nullable

The JSON Schema comparison checks directional acceptance and reports equivalent, different, or undetermined. A validated counterexample demonstrates a specific difference; unsupported constructs or missing proof remain undetermined. OpenAPI detector findings have their own recorded classification rules. Schema comparison is not a complete OpenAPI upload diff or proof of repository impact. Use public or illustrative schemas, inspect the evidence, and run your own CI before merging.

Explore API specification history · Contract and repository coverage