Diff Checker
Paste two versions of any text or code and see exactly what changed. Line, word, or character-level diff with color-coded output. Unified and split view, ignore-case and ignore-whitespace options.
Diff modes compared
Compares entire lines. Any line that changed — even by one character — shows as a removal (red) and an addition (green). Best for code review, config files, and log comparison.
Splits text into words and diffs those. You see exactly which words changed within a line without the whole line being marked. Best for prose, documentation, and JSON values.
Every individual character is compared. Useful for spotting single-character typos, off-by-one errors, or subtle punctuation differences that line and word diff would obscure.
Common use cases
Compare a function before and after a refactor to verify only the intended lines changed.
Spot differences between development and production config files, or two versions of a Dockerfile.
Compare JSON API responses from two environments to find unexpected field changes or missing keys.
Review what changed between two drafts of a spec, README, or email without tracking changes in Word.
Frequently asked questions
What diff algorithm is used?
The tool uses the Myers diff algorithm (via the diff.js library) — the same algorithm used by Git. It produces the shortest edit script: the minimum number of additions and deletions needed to transform the original text into the modified text.
What is the difference between line, word, and character diff?
Line diff compares entire lines — like `git diff`. A changed line shows as one removal and one addition even if only one word changed. Word diff splits text into individual words and compares those — you see exactly which words changed within a line. Character diff is the finest granularity — each individual character is compared, useful for spotting small typos.
When should I use unified vs split view?
Unified view shows both original and modified content in a single column with +/- markers — compact and familiar to anyone who has used git diff. Split view shows the original on the left and the modified on the right side by side — easier to read when the changes are structural or when you want to see context on both sides simultaneously.
Is my content uploaded?
No. The diff runs entirely in your browser using JavaScript. Nothing you paste is sent to any server.
Can I compare JSON, code, or structured data?
Yes. The tool works on any plain text — JavaScript, Python, SQL, JSON, Markdown, config files, log lines, prose. For JSON specifically, consider pretty-printing both sides with the JSON Formatter first so that structural differences appear as line changes rather than a single-line diff.
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