Diff Checker — Compare Text
See line-by-line differences between two blocks of text.
Files are processed in memory and never stored.
Paste two versions of any text and instantly see what changed — added lines highlighted, removed lines struck through, unchanged lines in place. Great for comparing drafts, config files, code snippets or API responses without any tooling.
How to use it
- Open the Diff Checker.
- Paste the original text on the left and the changed text on the right.
- The differences are highlighted line by line as you type.
How the comparison works
The tool computes a line-based diff using the longest-common-subsequence algorithm — the same core idea behind the 'diff' command and the change view in version-control tools. It finds the largest set of lines the two texts share in order, then marks everything else as added or removed. The result reads naturally: matching lines line up, and only the real changes stand out.
When a quick diff helps
You don't always want to open a full editor or commit to version control just to answer 'what changed?'. Comparing two pasted error logs, two versions of a JSON config, a colleague's edit against your draft, or two API responses is faster here. Because it runs locally, you can safely compare sensitive content like configuration or contracts.
Frequently asked questions
Is it a line diff or a word diff?
Line-based: it compares and highlights whole lines that were added or removed.
Is my text uploaded?
No — the comparison runs entirely in your browser.
Can I compare code?
Yes. Any text works, including code, JSON, logs and prose.
Does order matter?
Yes — put the original on the left and the new version on the right for the clearest result.
Is there a size limit?
Only your browser's memory; very large texts compare more slowly.
Is it free?
Yes — free and unlimited.