Why compare JSON side by side?
When you're debugging an API, reviewing a config change, or verifying a database migration, eyeballing two JSON blobs is painful. This tool runs a line-level diff between any two documents and paints the result so additions, deletions, and modifications jump out immediately. No signup, no upload — everything runs in your browser's JavaScript runtime.
Quick Start
- 1Drop your baseline JSON into the Original panel on the left.
- 2Drop the changed version into the Modified panel below it.
- 3Hit Compare — the right panel renders the diff with color-coded lines.
- 4Green = added, red = removed. Scroll through to review every change.
What you get
- Line-level precision — Powered by the diff algorithm — the same engine behind Git's text diffing.
- Visual color coding — Additions in green, deletions in red. No ambiguity.
- Full syntax highlighting — Both editor panels render your JSON with proper key/value coloring via
CodeMirror. - Zero network calls — Your data stays on your machine. Nothing leaves the browser tab.
When this is useful
- API regression testing — Capture a response, make a change, capture again, and diff the two to see exactly what shifted.
- Infrastructure config audits — Compare staging vs. production Terraform outputs, Kubernetes manifests, or CI pipeline configs.
- Data pipeline validation — Diff a sample payload before and after a transform step to verify your ETL logic.
- Pull request review — Paste JSON fixtures from a PR and verify the diff matches the intended change.
Frequently asked questions
Keys are in a different order — will that show as a change?
Yes. The diff is text-based, so reordered keys produce line differences. If you want a semantic comparison regardless of key order, sort both documents first using the JSON Sorter tool, then diff the sorted output.
Is there a size limit?
No hard limit. The diff runs in-browser, so performance depends on your device. Documents up to a few MB diff in under a second on modern hardware.
Does this send my data anywhere?
No. The entire comparison runs locally in JavaScript. There are no API calls, no telemetry on your input data, and no server-side processing.