JSON Diff Checker

Compare two valid JSON values by path and separate additions, removals, and changed values. The tool is for structural inspection, not for deciding whether two serialized files are byte-for-byte identical.

Browser-localFreeNo upload required

Tool workspace

Left JSON

Right JSON

Copy-ready summary

Advanced / Raw output

What this tool is for

Compare two valid JSON values by path and separate additions, removals, and changed values. The tool is for structural inspection, not for deciding whether two serialized files are byte-for-byte identical.

How to use

Paste the before value on the left and the after value on the right.
Run the comparison after both inputs pass JSON parsing.
Review each changed path and confirm whether array order is meaningful in your data.

Example

Compare two user records where `role` changed and a `verified` field was added; review the two reported paths before updating a fixture.

FAQ

Are arrays order-sensitive?

Yes. Values are compared at their array indexes.

Does whitespace create a difference?

No. Both inputs are parsed before comparison.

Reproducible examples

Known inputs and expected results

Run these examples in the workspace above and compare the result with the documented output.

Added and changed fields

Input: Before {"role":"viewer"}; after {"role":"editor","verified":true}
Options: Compare parsed values by path.
Action: Run the diff.
Expected output: role is changed and verified is added.
Explanation: The report separates a changed scalar from a newly present key.

Array index change

Input: Before {"tags":["a","b"]}; after {"tags":["b","a"]}
Options: Keep array order significant.
Action: Run the diff.
Expected output: Changes are reported at tags[0] and tags[1].
Explanation: The tool does not infer a move; array elements are compared at their indexes.

Error or unsupported case

Invalid right-hand JSON

Input: Left {"ok":true}; right {"ok":}
Expected error or limit: Comparison stops and identifies the invalid side.
Safer alternative: Correct both JSON values before interpreting structural changes.

When not to use this tool

Byte-for-byte file comparison
Move detection, date semantics, or numeric tolerance rules

Algorithm and assumptions

Both sides are parsed first; object paths are compared recursively, array order is significant, whitespace is ignored, and missing differs from explicit null.

Input and output

Inputs are two JSON values. Output is a path-based change list with before and after values where applicable.

Supported formats and behavior

Nested objects and arrays
Added, removed, and changed paths
Syntax validation for both inputs

Limits

No move detection for reordered arrays
No semantic rules for dates, identifiers, or numeric tolerances

Edge cases and common errors

A missing key differs from a key set to null
Array reordering may produce several changes
Invalid input stops the comparison

Release testing

Release checks cover nested objects, added and removed keys, changed scalars, arrays, equal values, and invalid input on either side.

Privacy boundary

The input and result stay in this browser session. ZZP Box does not upload or store the values entered in this tool.

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