JSON Diff — compare two JSON documents

Free, no signup, runs entirely in your browser — your data never leaves your device.

Structural comparison of any two JSON values: objects are compared key-by-key (order-independent), arrays index-by-index. Every difference is reported with its JSON Pointer path (/users/1/email) and the before/after values. Ask for patch=true to also get an RFC 6902 JSON Patch, verified to transform a into b.

API — GET /api

curl "https://json-diff-formatho.filesformatho.workers.dev/api?a=%7B%22a%22%3A1%7D&b=%7B%22a%22%3A2%7D"

curl -X POST https://json-diff-formatho.filesformatho.workers.dev/api \
  -H 'Content-Type: application/json' \
  -d '{"a":"{\"v\":1,\"keep\":true}","b":"{\"v\":2,\"keep\":true,\"new\":[1,2]}","patch":true}'

Parameters: a, b — JSON documents as strings (POST may also send pre-parsed objects); patch — true to include RFC 6902 ops. Limit 1MB per document.

Example response

{"equal":false,"counts":{"added":1,"removed":0,"changed":1,"type_changed":0},
 "diff":[{"path":"/v","op":"changed","before":1,"after":2},
         {"path":"/new","op":"added","after":[1,2]}]}

Private by design

Runs on Cloudflare's edge — no accounts, no logging, no cookies. For fully in-browser diffing use the full JSON diff tool on formatho.com.

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