JSON Diff
Compare two JSON documents and see exactly what changed — offline.
Your data is processed entirely in your browser and is never uploaded.
Tool workspace
Live diff is on — differences appear as you type.
$ diff a.json b.json
Paste two snippets above — or load the sample — and the differences render here, line by line, the instant they change.
Showing the first 20,000 lines of a very large diff.
Compare JSON in three steps
Paste both sides
Original in A, modified in B. The diff runs as you type — no upload, no waiting.
Read the changes
Additions in teal, deletions in red, changed lines facing each other. Toggle unified for a single column.
Tune & export
Ignore whitespace or case to cut noise, then copy or download the unified patch.
Frequently asked questions
Is either document uploaded?
No. The comparison runs entirely in your browser, in a background worker for large inputs. Neither side ever leaves your machine.
Why do some changed lines face each other?
When a line is removed and another added in the same place, the diff pairs them onto one row so you can read the before/after at a glance, instead of scrolling a delete block against an insert block.
What does the similarity score mean?
It's the share of lines that are identical on both sides, as a percentage of all lines involved. 100% means identical; 0% means nothing in common.