Diff Checker
Compare two blocks of text side-by-side and highlight added, removed, and changed lines. Runs entirely in your browser.
Use this free diff checker to compare two blocks of text and see exactly what changed. Switch between line-level and word-level views, ignore whitespace or case when you don't care about them, and spot every addition or removal at a glance — all without your text leaving the browser.
How to use it
No account, no upload — it all happens on your device.
When line diff beats word diff (and vice versa)
Pick the granularity that matches the change you care about.
| Use line diff for | Use word diff for |
|---|---|
| Source code reviews | Edited paragraphs of prose |
| Config files and YAML / JSON | Marketing copy and emails |
| Git-style change inspection | Translation comparisons |
| Log file comparisons | Spot single-word substitutions |
| Large multi-line patches | Headlines, slogans, titles |
Line diff treats each newline-bounded run of text as the atomic unit. A one-character change in a long line still highlights the whole line. Word diff goes finer: only the changed words are coloured, which makes prose edits much easier to spot but turns code diffs into noise.
What Ignore whitespace and Ignore case actually do
They normalise both inputs before diffing, not the displayed text.
- Ignore whitespace collapses runs of spaces and tabs to a single space and strips trailing/leading whitespace on each line. Two files indented with two spaces vs four will compare as identical.
- Ignore case lowercases everything before comparing.
Hello,HELLO, andhelloare all the same string. - Both options apply beforethe diff runs, so if the only changes are whitespace or case, you'll see a single "identical" badge and no highlighted diff.
Where this fits in your toolbox
For code, git diff, GitHub PRs, and editor diff views remain the gold standard — they understand language syntax, file structure, and history. This tool fills the gap when you have two ad-hoc strings that aren't in version control:
- Two API responses that should be identical and aren't.
- Email copy from a colleague vs your latest draft.
- Two pasted log lines where a timestamp or ID is the only difference.
- Comparing CMS exports before re-uploading.
- Bug reports — what the user said vs what your error message actually says.
Because everything runs in the browser, you can paste sensitive text (customer support transcripts, internal docs, private configs) without it leaving your device — useful in contexts where pasting into a third-party diff site would be off-limits.