utilyfe

JSON Diff

Find what really changed between two API responses, without the noise of key order or indentation.

Runs entirely in your browser. Nothing you enter is uploaded or stored.

Also try:JSON FormatterText DiffJSON Tree Viewer

How to use the JSON Diff

  1. 1Paste one document on the left and the other on the right.
  2. 2Read the list of changes, each addressed by its path, such as user.roles[1].
  3. 3Switch to Side by side to see both documents with keys sorted, which is easier for large payloads.
  4. 4Turn on "compare contents, not order" when the order of an array doesn't matter.

Comparing data, not characters

Two responses from the same API can be identical in meaning and completely different as text: keys in another order, different indentation, one of them minified. A text diff shows all of that as noise, and buries the one field that actually changed.

This tool parses both sides first and then walks the two values together, reporting each difference with the path that leads to it:

~ user.name        "ada" → "grace"
+ user.roles[2]    "admin"
- meta.legacyId    4821
! order.total      string → number

That’s usually all you need: what changed, and where to look.

What counts as a difference

  • Added or removed keys are reported at the path where they appear.
  • Changed values show both the old and the new.
  • Type changes are called out separately, because "7" and 7 behave differently once something consumes them.
  • Key order is ignored. JSON objects are unordered, so two documents with the same pairs match regardless of how they were written.
  • Array order matters by default, because position usually carries meaning. When it doesn’t (a set of tags, a list of permissions), turn on “compare contents, not order” and only genuinely added or removed items are reported.

Missing, null, and empty

Three states that get conflated and shouldn’t be:

State Reported as
The key isn’t there added or removed
The key is there and null a type change, if the other side has a value
The key is there and "" or [] a changed value

If your API distinguishes “not provided” from “explicitly cleared”, this is where you see it.

The side-by-side view

The list of paths is the quickest way to see what changed. For a large payload, or when you want the shape of the whole document, switch to side by side: both documents are pretty-printed with their keys sorted, then compared line by line.

Sorting is what makes that view usable: without it, a reordered key would push everything below it out of alignment and make the whole document look different.

Numbers, precision and long ids

JSON numbers are parsed as standard floating-point values, so an identifier longer than about 16 digits loses precision on both sides before the comparison happens. Two different ids can arrive here looking identical.

It’s the same limitation every JSON parser has, and the fix is the same: send long identifiers as strings.

Questions

How is this different from a text diff?
A text diff compares characters, so it reports every reordered key, every change of indentation, and treats a minified document as one enormous line. This parses both sides and compares the data, so it reports only what changed and tells you exactly where, by path.
Does key order count as a difference?
No. JSON objects are unordered by definition, so two documents with the same keys in a different order hold the same data. Array order is different: that one does matter, and it's compared by position unless you say otherwise.
Why does it say the type changed rather than the value?
Because "7" and 7 are different things to almost every consumer, and this catches a common class of API bug where a field quietly changes from a number to a string. The same applies to null, which is reported as its own type rather than as an empty value.
Is a missing key the same as a null one?
No, and the difference matters. A key that isn't there is reported as added or removed; a key that's present and null is reported as a value or type change. Many APIs treat the two differently.
Is my data uploaded?
No. Both documents are parsed and compared in this browser tab, which matters when you're diffing a real API response. Nothing is uploaded, logged or saved.