JSON Diff – Free Online Tool
Free online JSON Diff tool to compare two JSON objects and find differences instantly. Highlight added, removed, and changed properties between JSON structures. Perfect for debugging API responses and comparing configuration files. All comparison happens locally.
Example Output
Field-level diff showing only what actually changed, ignoring formatting.
CHANGED age: 30 → 31 (1 difference)
What is JSON Diff?
JSON Diff compares two JSON documents at the value level and reports added, removed, and changed keys. Unlike a textual diff, it ignores whitespace and key order so reformatting doesn't produce false positives. Useful for API response comparisons, config audits, and quick spot-checks during pull-request review.
Why use this tool?
- Stable behavior across visits — no surprise version drift
- Your data stays private — all processing happens locally in the browser
- No telemetry, no tracking pixels, no third-party scripts
- Works with very large inputs (multi-megabyte JSON, long regex patterns, big tables)
- No telemetry on the tokens, payloads, or code you paste in
How to use
- Paste your "before" JSON in the left textarea
- Paste the "after" JSON in the right textarea
- Click Compare — additions, removals, and value changes are highlighted
- Use it during code review to spot semantic differences past whitespace
Examples
Spot a regression in an API
Save the production response and the staging response into the two panes — the diff surfaces exactly which fields drifted.
Config audit
Compare old and new versions of a feature-flag config to confirm only intended keys changed.
Common use cases
- Comparing API responses across versions or environments
- Reviewing JSON-based configuration changes in a PR
- Validating data migrations by comparing pre/post snapshots
- Debugging "why is the value different?" on near-identical payloads
Troubleshooting
- Diff reports a change but values look identical.
- Look for type mismatches: "30" (string) vs 30 (number) is a real difference. Trailing whitespace inside strings also counts.
- Diff says no change but I see one visually.
- Whitespace and key order are ignored by design. To compare formatting, use a plain text diff tool instead.
Frequently Asked Questions
The tool parses both JSON inputs and recursively compares their structure, highlighting any differences in values, added or removed keys, and type changes.
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