Problem solved by Diff Anything
Learn how to review baseline and candidate OpenAPI contracts, run a free local compatibility check, and continue the detailed review in Diff Anything.
See it in the app
No accounts, cloud comparison service, analytics, or telemetry.
The problem
A source diff can overemphasize reordered YAML while a removed operation, newly required parameter, narrowed enum, or response schema change is buried elsewhere in the contract. Compatibility also depends on which document is the existing baseline.
The solution
Compare the contract from the perspective of an existing consumer. The free browser checker classifies likely breaking, review-needed, and compatible changes locally; Diff Anything provides the focused desktop workflow for recurring OpenAPI and JSON Schema comparisons.
Free local checker
The focused tool accepts Swagger 2.0 and OpenAPI 3.0/3.1 JSON or YAML, keeps the specifications in the browser tab, and exports Markdown or JSON reports.
01 / Compatibility review
The baseline describes what current consumers already depend on. The candidate is the proposed replacement. Reversing them reverses the meaning of removal, addition, narrowing, and new requirements.
Keep both source versions available. A rule classification helps prioritize review; it does not decide whether a product-specific behavior is acceptable.
02 / Compatibility review
Removed paths, operations, parameters, properties, or enum values can break a consumer. Newly required input and narrower accepted types also deserve immediate attention. Additions are often compatible, while type, schema, security, and response changes can require context-dependent review.
Start with the reported breaking group, then inspect review-needed findings against actual clients and implementation behavior. A clean report cannot prove compatibility beyond the contracts and rules the checker examined.
03 / Compatibility review
The free checker accepts Swagger 2.0 and OpenAPI 3.0/3.1 in JSON or YAML. It resolves internal references, but it does not fetch external references; it reports a warning when they remain outside the comparison.
Schema traversal uses a depth limit of eight. The output is a heuristic compatibility report, so important releases still need client tests and human review of runtime behavior, undocumented expectations, and semantic meaning.
Clear answers
No. Parsing and comparison run in the current browser tab; the specifications are not uploaded to martingruner.com.
The browser checker accepts Swagger 2.0 and OpenAPI 3.0 or 3.1 descriptions in JSON or YAML.
No. The report is heuristic and limited to the parsed contracts and implemented rules. External references, deep schemas, runtime behavior, client assumptions, and semantic meaning can still require testing and human review.
Three short steps
Use the existing consumer contract as the baseline.
Open or paste the candidate contract into the local checker.
Review likely breaks first, then verify context-dependent behavior and clients.
Available for macOS and Windows