100% Client-side · Your JSON never leaves your browser
Compare Two JSON Files Side by Side
Spot the difference with line + word-level highlighting. Perfect for diffing API responses, configs, or fixtures.
JSON Tools
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Beautify — pretty-print with 2-space indentation. Cmd+Enter to run
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Output
Mode
Indent
Paste JSON and it updates live.
Or press Cmd+Enter.
FAQ
JSON Diff — Frequently Asked Questions
Common questions about the JSON compare tool, line vs word diff, and large-file behavior.
How does this online JSON diff tool work?
Paste two JSON payloads side by side. We pretty-print both inputs, run a longest-common-subsequence diff over the lines, then a secondary word-level diff inside changed lines for granular highlighting.
Can the JSON compare tool ignore key order?
Today the diff is line-based after pretty-printing — if your inputs differ only in key order they will look different. A semantic JSON compare mode (key-order-insensitive) is on the roadmap.
Is my JSON data sent to a server when comparing?
No. Both inputs are diffed entirely in your browser. We have no servers and store nothing — perfect for diffing sensitive API responses, configs or fixtures.
What size JSON files can the diff handle?
Hundreds of KB diff comfortably. Multi-MB inputs are doable but the LCS algorithm becomes the bottleneck — split the diff if it slows down on very large files.
Does the JSON diff highlight word-level changes?
Yes. Inside any changed line we run a secondary word-level diff so a single typo in a long string value is highlighted, not lost in a sea of identical text.
Can I diff JSON5 / JSONC files with this tool?
Run the inputs through the JSON Formatter Auto-Fix first to strip comments and trailing commas, then paste the cleaned output here for a strict line-by-line JSON compare.
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