Text Diff Checker
Paste two versions of any text and see exactly what changed. Runs entirely in your browser. Nothing you paste is ever uploaded.
What can you compare?
DiffLens highlights exactly what changed between two blocks of text. Two drafts of an essay, two versions of a config file, two revisions of a contract clause, or any pair of texts you need to compare. Switch between line mode (best for code and paragraph-level edits) and word mode (best for spotting small wording changes within a sentence).
Curious how diff tools actually decide what counts as changed? Read How Diff Algorithms Actually Find Differences.
How it works
DiffLens compares your two texts directly in your browser using a standard longest-common-subsequence diff algorithm, the same approach behind most diff tools, so nothing is ever sent to a server. Additions are highlighted in green, removals in red, and unchanged content stays plain.
Frequently asked questions
Is this free to use?
Yes. There's no sign-up and no limit on how many comparisons you run.
Do you store the text I paste in?
No. The comparison runs entirely client-side in your browser. See the privacy policy for details.
What's the difference between line and word mode?
Line mode compares whole lines, good for code, config files, or paragraph-level edits. Word mode compares word by word, better for spotting small wording changes within a sentence.
Is there a size limit?
Very large pastes (roughly over 3000 lines or words per side) are rejected with a message asking you to compare smaller sections, to keep the comparison fast in your browser.