What is a Text Diff Checker?
A text diff checker compares two pieces of text and highlights exactly what changed — added in green, removed in red, and unchanged in plain text. It’s the fastest way to review document revisions, compare code versions and audit content edits.
This checker compares by character, word or line using a real diff algorithm, with inline, side-by-side and unified views and similarity analytics — all privately in your browser. To edit the result, pair it with Find & Replace or the Grammar Corrector.
Compare & Review
How text comparison works
Paste both texts
Drop your original into panel A and the modified version into panel B — or upload text files. Everything stays in your browser.
Pick a granularity
Compare by character, word or line, and ignore case, whitespace or punctuation to focus on real changes.
See the diff
Additions show green, deletions red. Switch between inline, side-by-side and unified views.
Export the report
Copy the diff or download a TXT, PDF or DOCX report with the full unified diff and statistics.
Diff vs similarity analysis
Difference (diff)
- Shows the exact edits — what was added, removed and kept.
- Order-aware: it aligns matching content and marks the rest.
- Answers “what changed and where?”
Similarity
- Reduces the comparison to a single percentage of overlap.
- Good for a quick “how close are these?” signal.
- Answers “how much is the same?” — not where.
Key benefits
Real LCS diffing
Uses the Longest Common Subsequence algorithm — the same method behind Git — for precise, minimal diffs.
Three views
Inline highlights, a side-by-side aligned table, and a unified +/− diff like a code review.
Similarity analytics
Similarity %, additions, deletions, line changes and A-vs-B word, character and reading-time stats.
Smart options
Ignore case, whitespace and punctuation to cut noise — ideal for code reformatting and prose edits.
Private by design
Both texts are compared locally. Nothing is uploaded or stored — safe for confidential documents and code.
Free, no sign-up
Unlimited comparisons with no account, no email and no watermark, plus TXT, PDF and DOCX export.
Document & code comparison use cases
Developers
Compare code versions and config files line by line, ignoring whitespace to see only logic changes.
Editors & writers
Track revisions between drafts and see exactly what an edit added, removed or reworded.
SEO professionals
Audit content changes across page versions and confirm updates without losing key passages.
Legal & business
Compare contract and policy versions to surface every clause that changed between revisions.
Students & researchers
Compare drafts, check quotes against sources, and verify how much text actually changed.
Translators & QA
Diff source and updated strings to catch missed updates and untranslated changes.
Best practices
Match granularity to content
Use word diff for prose, line diff for code and data, and character diff to chase down tiny typos.
Ignore noise
Turn on “Ignore whitespace” for reformatted code and “Ignore case” when capitalization doesn’t matter.
Use the right view
Inline for quick scanning, side-by-side for reviews, unified for a clean +/− report to share.
Swap to verify direction
Click “Swap” to flip A and B — useful for confirming whether content was added or removed.
Common mistakes to avoid
- Comparing by character on long documents, which makes prose changes hard to read — use word diff.
- Forgetting to ignore whitespace when code was only reindented, drowning real changes in noise.
- Reading similarity percentage as a true plagiarism score — it measures token overlap, not intent.
- Pasting two unrelated texts and expecting a clean diff; comparison works best on versions of the same content.
Frequently asked questions
A text diff checker compares two pieces of text and highlights exactly what changed — what was added, removed or kept the same. It’s used to review document revisions, compare code versions, audit content edits and spot differences between two drafts. This tool compares in real time, with color-coded highlighting, entirely in your browser.
The tool breaks both texts into tokens — characters, words or lines depending on the mode — and runs a Longest Common Subsequence (LCS) algorithm, the same approach behind version-control diffs. It finds the largest set of matching tokens, then marks everything else as an insertion or deletion, giving you a precise, minimal diff.
Character comparison shows every changed letter — best for spotting tiny edits and typos. Word comparison highlights changed words while keeping unchanged ones intact — best for prose. Line comparison treats each line as a unit — best for code, lists and structured documents. Switch modes to match your content.
Green highlights content that was added in the modified text, red highlights content removed from the original, and unchanged content stays plain. In the side-by-side view, rows are aligned and color-coded as added, deleted, modified or equal so you can scan changes at a glance.
Yes. Toggle “Ignore case” to treat “Hello” and “hello” as identical, “Ignore whitespace” to skip differences in spaces and indentation, and “Ignore punctuation” to compare just the words. These options reduce noise so you see only the changes that matter.
The similarity percentage is the share of content that is identical between the two texts, based on the diff. 100% means the texts match exactly; a lower number means more was added or removed. It’s a quick signal for how close two versions are and a rough indicator of duplicated content.
Yes. Use line comparison for code, JSON and CSV — it aligns line by line the way developers expect, and the side-by-side view mirrors a code-review diff. Turn on “Ignore whitespace” to focus on real logic changes rather than reformatting.
Yes. It is 100% free with no sign-up, and all comparison happens locally in your browser — neither text is uploaded or stored. You can copy the results or export a diff report as TXT, PDF or DOCX.
Written by Omnitool Editorial Team
Our content is crafted by software engineers and content specialists to guarantee algorithmic accuracy, transparent methodology, and complete user privacy. Co-reviewed by senior SEO strategists.