JSON compare — catch payload drift fast
Nested objects hide small breaks: a missing field, a string that became a number, an array element that moved. CheckDiffs lets you paste baseline and updated JSON, highlight with Monaco’s JSON mode, and jump between changes — all in the browser. Nothing uploaded for basic compare.
Open JSON compareHonest limit: line diff, not a tree engine
Set the homepage language selector to JSON. Paste the known-good payload on the left and the new response on the right. For readable hunks, pretty-print both sides with the same indentation first. We intentionally do not claim deep key-sorting or semantic merge — if you need a structural JSON tree-diff, that is a different class of tool.
Typical uses: API responses before and after a deploy, config exports a teammate tweaked, AI-generated fixtures against your original, or feature-flag packs between environments.
Keep fixtures local
Production-like responses can contain PII or secrets. Basic compare stays on your device. Privacy · About
FAQ
Is my JSON uploaded?
No. Comparison runs in your browser with Monaco. Pasted JSON stays on your machine for basic side-by-side. You should not see your payload posted to checkdiffs.com in DevTools → Network.
Does this pretty-print or deep-sort keys?
No. CheckDiffs is a text/line diff with JSON syntax highlighting — it compares what you paste. Pretty-print both sides the same way before comparing. We do not claim a semantic tree-diff engine.
Can I compare minified JSON?
You can, but one long line makes hunks hard to read. Format both sides first, then paste.
Is it free?
Basic side-by-side is free forever, no account. Pro ideas (export, ads-free, AI summary quota) are TBD — no fake payment flow.
Set language to JSON at checkdiffs.com, paste both payloads.