JSON Diff Viewer

What This Tool Does

The JSON Diff Viewer performs a deep, structural diff between two JSON documents. Unlike a text diff (like git diff), it doesn't care about whitespace, key order, or line breaks. It walks the tree on both sides and reports differences by path: which keys are new, which are gone, and which have different values.

Every difference is reported with the full JSON path (user.address.city, orders[2].total) so you can jump straight to what changed without hunting through nested objects. Nested changes are surgical — if only one field inside a deep object is different, only that field is highlighted, not the whole parent.

When To Use It

• Debugging API responses. Same request, different responses on staging and prod? Paste both, see exactly which fields diverged.
• Config file review. Comparing two environments' config.json, package manifests, or Terraform-emitted state.
• Schema changes. When an upstream service adds or renames a field, this tool tells you what changed at the payload level.
• Test snapshot debugging. Jest / Vitest snapshot mismatches often make more sense as a JSON diff than as a raw text diff.
• Feature-flag audits. Comparing config for a flagged rollout vs. control.

How the Diff Works

The algorithm walks both trees recursively:

1. If both sides are the same primitive value at the same path — unchanged.
2. If the path exists only on the right — added (green).
3. If the path exists only on the left — removed (red).
4. If the path exists on both sides with different values — changed (amber), and the diff shows both the old and new value.
5. Nested objects and arrays are diffed recursively, so you get the smallest possible highlight for any change.

Two toggles change the behavior:

• Ignore array order. By default, arrays are compared index-by-index. With this on, arrays are compared as sets — [1,2,3] vs [3,2,1] reports zero differences.
• Ignore string case. Compares strings case-insensitively ("Alice" equals "alice"). Useful for user-input fields where casing shouldn't count.

Privacy

Everything runs in your browser. Your JSON is never sent anywhere — no API, no logging, no storage. You can verify this by opening your browser's DevTools Network tab and running a diff. Zero requests fire. This matters if you're comparing production data, PII, or anything sensitive.