Text Diff Checker Online — Compare Two Texts and Find Differences
Compare two texts
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Compare two texts side by side and instantly see which lines were added, removed, or left unchanged — additions are tinted green, deletions red, and identical lines stay neutral so the delta is obvious at a glance. An efficient LCS-based diff algorithm keeps the comparison fast and accurate even for long documents, with no artificial size cap on input. Run a content audit to verify title-tag and meta-description edits before publishing, review editor feedback against your original draft, or compare legal and compliance text versions to confirm exactly what changed between revisions. Everything runs 100% locally in your browser — sensitive contracts, NDA drafts, and unpublished content never leave your device. There are no servers, no accounts, and no upload limits — paste your text and get the diff instantly.
Line-by-line comparison for edits, contracts, and source code
Paste two versions of a contract, an SEO rewrite, or a code snippet and the diff view highlights every added line in green, every removed line in red, and unchanged context in between — making it obvious which clauses moved, which paragraphs were cut, and which lines were rewritten. The underlying algorithm is an efficient longest-common-subsequence pass that stays responsive on multi-thousand-line inputs. Use it before every content revision to make sure no keyword phrase, legal clause, or code branch was lost in the edit.
Local diff for confidential and regulated text
Everything is compared in your browser with no upload, no logging, and no API call — important for NDAs, MSA redlines, HIPAA-protected patient notes, and source code covered by an NDA. Drop in two chunks of any length and the diff appears instantly, with no file-size warnings and no third-party service in the middle. That makes it safe to use on real client work that a SaaS diff tool would block under its terms of service.
Frequently Asked Questions (FAQ)
Paste two versions of a text into the left and right inputs and the tool runs an efficient longest-common-subsequence algorithm to produce a line-by-line diff. Added lines are highlighted in green, removed lines in red, and unchanged context is shown between them — so you can see at a glance exactly what moved, what was cut, and what was rewritten.
Contracts, SEO rewrites, code snippets, configuration files, translations, and any other pair of texts where you need to verify what changed between revisions. Use it before publishing a content update to make sure no keyword phrase, legal clause, or code branch was lost in the edit.
No. The LCS-based algorithm stays responsive on multi-thousand-line inputs, and there is no length cap on either side. Large contract redlines and full source files compare without warnings.
The comparison is line-level: a line is marked added, removed, or unchanged as a unit. This is the right granularity for legal and editorial review, where a single word change inside a long line still shows up as the whole line being removed and re-added.
The diff highlights added and removed lines but does not apply language-specific syntax highlighting. For source-code review, the line-level color coding is usually enough to spot which branches moved between revisions.
No. The diff is computed entirely in your browser with no upload, no logging, and no API call. That makes it safe to use on NDAs, MSA redlines, HIPAA-protected patient notes, and source code covered by an NDA.
Yes. Two toggles sit above the input fields: Ignore Whitespace collapses repeated spaces and tabs and trims trailing spaces before comparing, and Ignore Case lowercases both texts so a change from "Article" to "article" no longer flags the line. Flip them on or off at any time — the diff recalculates instantly, so you can compare a reformatted document without drowning in formatting noise.
Three view modes: Diff only shows just the added and removed lines, Full text renders the whole document with changes highlighted in place, and Side-by-side puts the two versions in synchronized columns that scroll together. A live stats bar counts the added, removed, and changed lines. You can copy the diff as plain text or as colored HTML — ready to paste into emails and documents — and download it as a standard unified .diff patch or a plain .txt file.