Add JSON A
Paste or upload the first JSON document in the left editor.
JSON Compare Guide
JSON Sync - Compare, Diff and Sync JSON Online
Use JSON Sync as a JSON compare, JSON diff, formatter and validator for nested JSON comparison with local file upload, line highlights, stats, and one-click sync.
How to use JSON Sync
Add JSON B
Paste or upload the second JSON document in the right editor.
Validate input
Invalid pasted text or uploaded files show an error before comparison.
Review changes
Search and filter differences by path, missing key, value or type.
What each section means
Stats
A summary of match rate, leaves, missing keys, type changes and value changes.
Line Highlights
A line-number view that marks where each changed path appears.
Differences
A searchable table of path-level differences with sync actions.
Sync Buttons
Controls for uploading, formatting, swapping, syncing one path, or syncing the full document.
Compare two JSON files without losing nested context
API response comparison
Compare staging and production payloads to find changed fields quickly.
Configuration review
Review environment JSON files before copying values between configs.
Localization JSON checks
Find missing translation keys between locale files.
Test fixture updates
Inspect fixture changes before syncing expected JSON snapshots.
Privacy
Your JSON stays in the browser
JSON Sync reads uploaded files locally in the browser and compares pasted content in memory. The app has no server upload step for your JSON documents.
FAQ
Does JSON Sync upload my JSON to a server?
No. Pasted JSON and uploaded files are read in the browser and compared locally in the page.
What does JSON Sync compare?
JSON Sync compares objects, arrays, nested keys, scalar values, and type changes with source-line context.
Can I upload JSON files from my computer?
Yes. Each JSON editor includes an upload button, and invalid files show an error without replacing the current content.
What happens if an uploaded JSON file is invalid?
The editor shows a validation error and keeps the previous content unchanged.
Can I copy one JSON key or value into the other file?
Yes. Each difference row has one-click actions for applying a selected path in either direction.
Can I sync the full JSON document?
Yes. When both sides are valid, you can mirror JSON A to JSON B or JSON B to JSON A in one click.
Does JSON Sync highlight changed lines?
Yes. The line preview marks source lines that contain changed, missing, or mismatched JSON paths.
Can I format and validate JSON before comparing?
Yes. Valid JSON can be formatted, and invalid JSON is blocked from compare and sync actions until it is fixed.