Compare JSON Online

Comparing two JSON documents means answering three questions for every property: was it added, was it removed, or did its value change. Anything left over is unchanged, and a genuinely useful comparison tool should say so explicitly rather than making you infer it.

That's different from comparing JSON as plain text. Two files can be byte-for-byte different — different indentation, different key order, a trailing newline — while representing exactly the same data. A structural comparison sees through that and reports on the data itself.

Real-world JSON is rarely flat. Configuration files, API responses and data exports usually nest objects several levels deep, sometimes inside arrays of similar records.

A property path like orders[3].shipping.address.postalCode tells you precisely where a change happened, which is far more useful than a generic notice that 'the arrays differ.' Arrays are compared position by position, so inserting an item in the middle will show up as a change to everything after it — which is expected, since that's genuinely what happened to the array's contents.

Minified JSON — no line breaks, no indentation — is common in API logs and network captures, but it's unreadable in a diff. Comparing two minified files as plain text usually produces one giant 'line changed' result that tells you nothing.

Parsing both documents first removes the formatting from the equation entirely. Whatever indentation, spacing or minification either file originally used, the comparison is based on the parsed data, and the result view re-prints both sides consistently so you can actually read them.

Large exports and API responses can run into thousands of lines. The comparison itself only walks the parts of the structure that actually differ — matching subtrees are recognized and skipped rather than being re-checked property by property — so the summary stays fast even on sizeable documents.

For very large files, it's worth narrowing down what you're actually checking. If you only care about one section, pasting just that section on both sides will always be faster and easier to read than diffing an entire multi-thousand-line export.

Both panels are read and compared entirely inside your browser using JavaScript running on your own device. The content is never sent to a server, logged, or stored anywhere — closing the tab clears it completely.

That matters for JSON in particular, since it's often the format used for API responses, configuration files, and data exports that may contain internal identifiers or customer data. See the privacy page for the full explanation of what does and doesn't happen to your data.