API Contract Drift Checker
Compare two JSON Schema contracts from a generic, request, or response perspective. This page does not parse OpenAPI.
Baseline schema (OLD)
Previously accepted contract · JSON or YAML · 256 KiB maximum.
Baseline schema editorCandidate schema (NEW)
Proposed contract · JSON or YAML · 256 KiB maximum.
Candidate schema editorCompare contracts
Both validation directions are shown equally.
Semantic comparison
Ready to compare
Load an example or paste two Draft 2020-12 schemas, then choose Compare locally.
Request and response contract drift
Request mode emphasizes whether old valid requests are accepted by the new server contract. Response mode emphasizes whether a new allowed response could fail an old consumer contract. Both directions remain visible. This tool analyzes contract-level JSON Schema compatibility. Actual application behavior may differ.
Schema-level scope
Paste two JSON Schema Draft 2020-12 documents. This page compares two extracted schemas. The response validators below handle OpenAPI operation selection, status and media matching. The schema comparison is local, with no live API call or storage.
Privacy and indexability
Both inputs stay in browser memory and run in a browser worker. No provider, product backend, or analytics receives pasted schemas. Each schema is limited to 256 KiB and depth 64, with at most 500 reported changes and a 15-second worker timeout. Coverage becomes partial for unsupported semantics.
Open the general JSON Schema checker