API Response Diff
Compare a baseline API response with a new response and get an API-safe drift report: added fields, removed fields, type changes, changed values, array shape changes, a copyable contract review checklist, and a starter guard test pack. Everything runs in your browser.
Runs in your browser
Nothing uploaded
Free, no signup
Ctrl + Enter to run · Recent brings back your last inputs · Everything stays in this browser
API Response Diff: questions
What should I paste into API Response Diff?
Paste a known-good JSON response on the left and the new response on the right. The tool compares structure, types, and representative values without sending either payload anywhere.
What counts as a breaking API change?
Removed fields and type changes are flagged as breaking candidates because clients often depend on them. Added fields are usually non-breaking but still useful to review.
What is in the guard test pack?
The guard pack turns breaking drift into a small Node test that checks required paths and expected JSON types. It copies paths and types only, not raw response values.
Can I use it with arrays?
Yes. Arrays are summarized by item type and inspected through sample indexes so you can spot array-to-object changes, empty arrays, and changed item shapes.
How does this connect to JSON Schema?
Use API Response Diff to find drift and generate a focused guard, then send the reviewed response to the JSON Schema Generator for a broader contract and starter tests.
Related tools
All 112 free tools
JSON Formatter & ValidatorPretty-print & validate JSON
Image Resize CalculatorCalculate new dimensions while preserving aspect ratio
Password Strength CheckerAnalyze password entropy and weaknesses
YAML ↔ JSON ConverterConvert between YAML and JSON
JSON to YAMLConvert JSON to YAML format
JSON Schema GeneratorInfer and validate API contracts
Made something with AI? Share it as a private link.
Drop in the HTML from Claude, ChatGPT or any editor and get a link your client can open anywhere — with a password, view tracking, comments and approval.