About JSON Diff / Compare
This tool compares two JSON texts side-by-side, highlighting exactly what was removed (in red) and added (in green) between them — useful for comparing two versions of an API response, a config file before and after a change, or two similar records. By default, it ignores harmless differences in property order, so you see only the changes that actually matter. All comparison happens locally in your browser; neither JSON is ever sent to a server.
How the Comparison Works
Both JSON texts are first parsed and re-formatted with identical, consistent spacing — this means differences that come only from formatting (extra spaces, different indentation, trailing commas) never show up as false differences. With "Ignore key order" enabled, object keys are also sorted alphabetically before comparing, so {"a":1,"b":2} and {"b":2,"a":1} are correctly treated as identical, since JSON objects are unordered by specification — only the actual values matter. The tool then finds the differences using the same underlying approach as most diff tools (including git diff): it computes the Longest Common Subsequence (LCS) between the two formatted texts, treating everything in that shared sequence as unchanged and everything else as removed or added.
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