Both sides are pretty-printed before comparing. Differently-ordered keys in an otherwise-identical object will show as a diff.
Online JSON Compare & Diff Tool
Comparing two JSON payloads by eye is slow and easy to get wrong. Paste an API response before and after a change, two config file versions, or two test fixtures, and this tool highlights exactly which lines were added, removed, or changed — useful for debugging why a response shape shifted or reviewing a config diff before deploying it. It helps QA teams and API developers spot changed, added, or removed values between two JSON documents.
How to compare two JSON files online
Paste the original JSON into the left box and the changed version into the right box, then click Compare. Both sides are validated and pretty-printed first, so differences in spacing or indentation alone won't create false positives — you only see differences that reflect an actual change in the data.
Reading the diff result
Each changed line is marked with a + (added in the new version) or - (removed from the original), and a running count of additions and removals is shown above the diff. Unchanged lines are included for context, so you can see exactly where in the structure a change happened rather than just that something changed somewhere.
A note on key order
JSON objects have no inherent key order — two objects with the same keys and values but listed in a different order are logically equal, but this tool compares text line by line, so a reordered key will still show up as a diff. This is a deliberate trade-off: a true structural (order-independent) diff would hide real differences in arrays, where order does matter.
Common use cases
- Reviewing exactly what changed in an API response before and after a backend deploy
- Comparing two versions of a configuration file before merging a change
- Diffing test fixtures to understand why a snapshot test started failing
- Spotting an unexpected field addition or removal in a webhook payload
How to use JSON Compare for related tasks
Paste both objects, compare JSON documents, and use the highlighted difference paths to verify an API or configuration change.
Related tools: JSON Parser, Text Compare.
Frequently asked questions
Why does my JSON compare show differences even though the data looks the same?
Both sides are pretty-printed before comparing, so formatting alone (spacing, indentation) won’t cause false positives. But JSON objects have no inherent key order, so if the same keys appear in a different order on each side, that will still show as a diff even though the data is logically identical.
Is my JSON data uploaded anywhere when I compare it?
No. The diff is computed entirely in your browser using a local line-diff algorithm — neither side of the comparison is ever sent to a server.
What do the + and - markers mean in the diff result?
A green line marked "+" was added in the changed JSON; a red line marked "-" was removed compared to the original. Unmarked lines are unchanged and shown for context.
Can I compare very large JSON documents?
Yes, though the line-diff algorithm is capped at 5,000 lines per side to keep the comparison fast and avoid freezing the tab on extremely large payloads.
How do I compare two JSON objects?
Place the before and after documents in their matching panels; the diff view separates structural changes from unchanged content.