JSON Diff

How to use

1. Paste the before and after documents — an API response before and after a deploy, two config files, two fixtures.
2. Read the paths: each row names the exact place that changed.
3. Look for type changes first; they break clients more often than value changes.
4. Reformatting and key reordering will not show up, which is the point.

Features

• Compares values at paths, so key order and formatting are correctly ignored.
• Paths written the way code addresses them: `user.roles[0]`.
• Type changes reported separately from value changes.
• Arrays compared by index — boring, and always true.
• Runs entirely in your browser; neither document is uploaded.

Frequently asked questions

Why not a text diff of the formatted JSON?

Because a text diff answers a different question. Reorder two keys and it reports two changes where the document means the same thing; reformat a file and it reports a rewrite. Comparing values at paths reports only what a consumer of the JSON would actually notice.

Why are arrays compared by index rather than matched up?

Because matching by content is a guess. Insert an element at the front and a clever matcher either recognises the shift or reports every element as changed — and when it guesses wrong, the diff is worse than useless. By index the answer is dull and always correct; if you need order-insensitive comparison, sort both sides first.

What counts as a type change?

A value whose JSON type differs: `1` to `"1"`, an object to an array, anything to null. It is separated out because it is the change most likely to break a client — a string where a number was expected fails at the point of use, often far from where it was introduced.

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