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Json Compare🔒 100% local
Diff two JSON documents. Privacy-first, no server uploads, no tracking.
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Compares two JSON objects that you supply as two lines of one text box: line one is the left side, line two is the right. The result lists keys that exist only on the left with a minus, keys only on the right with a plus, and keys whose value changed with a tilde followed by old and new. Both objects are parsed in the page, so an API response you paste stays on your machine.
How to use it
- Put the first object on one line and the second on the next line.
- Press Process once both lines are in place.
- Read the diff in the output box - unchanged keys are not listed - and copy it if you need to record the difference.
Worked example
{"a":1,"b":2}
{"b":2,"c":3}becomes- a: 1
+ c: 3b appears on both sides with the same value, so it is left out. Keys present on both sides but different are printed with a tilde, as in the example below.
{"a":1}
{"a":2}becomes~ a: 1 → 2When to use it
- Comparing two captures of the same API endpoint before and after a deploy.
- Checking which feature flags or config keys a release added and removed.
- Finding the one field that differs between a staging and a production response.
What it does not do
- Only top-level keys are compared. A change one level down prints the whole nested object as old and new rather than pointing at the field that moved.
- The two inputs must each be a single balanced line; a pretty-printed object spans several lines, and each of those lines fails to parse, so the tool answers 'Invalid JSON (provide two objects separated by newline)'.
- Roots must be objects - an array or a scalar throws. A third line is parsed and then ignored, which can hide a mistake.