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Dev Tools
JSON Merge Patch Builder
Diff two JSON documents and emit a minimal RFC 7396 merge patch. Null deletes keys, objects deep-merge — simpler than RFC 6902. Apply-back verification, 100% client-side.
JSON Patch Builder
Diff two JSON documents and emit a minimal RFC 6902 patch (add, remove, replace, copy, move, test). Verifies the patch by re-applying it to the source — 100% client-side.
Generator
Mock API Response Generator
Generate realistic mock REST API responses with status codes, headers, pagination and error shapes. Export as JSON, raw HTTP, MSW handler, or curl.
OpenAPI Generator
Generate OpenAPI 3.0 (Swagger) specifications online. Build API info, servers, paths, parameters, request bodies, and responses. Export as YAML or JSON instantly.
Postman Collection Generator
Generate a Postman Collection (v2.1) JSON file from endpoint definitions, auth settings, variables, and request bodies. Live preview, copy, and download. Free online tool.