Text Diff Checker
Compare two texts and highlight the differences.
Enter text on both sides to see a line-by-line diff.
Use on any page (bookmarklet)
Want Text Diff Checker without leaving the page you're on? Drag the button below to your bookmarks bar, then click it on any website to open Text Diff Checker right there — it runs entirely in your browser.
Use responsibly: a bookmarklet runs on whatever page you click it on. Avoid sensitive sites such as online banking, payment, or healthcare pages — you run it at your own risk. Everything is processed locally and no data is sent anywhere. See our Terms.
- Show your bookmarks bar if it's hidden — Ctrl+Shift+B (⌘+Shift+B on Mac).
- Drag the button above onto the bookmarks bar.
- Open any website and click the bookmark — the Text Diff Checker panel appears in the top-right corner. Use ✛ to move it between corners, or ›/‹ to tuck it against the edge and pull it back out.
- Click the bookmark again (or the ✕) to close it.
Note: a few sites with strict security policies may block bookmarklets.
Examples
Edited and inserted lines
Input
Original: - bread Changed: - whole wheat bread (+ a new "- cheese" line)
Output
− - bread + - whole wheat bread + - cheese (+2 added · −1 removed)
Identical text
Input
Both sides the same
Output
Identical — no differences
About this tool
This free online text diff checker compares two pieces of text and highlights exactly what changed, line by line. Paste an original and a changed version and it marks added lines and removed lines with line numbers for each side. It's perfect for comparing document drafts, code versions, configuration files, or any two blocks of text — and it all runs in your browser with no upload.
How to use
- Paste the original text into the left box.
- Paste the changed text into the right box.
- Read the highlighted differences below, with added and removed counts.
- Optionally ignore case or whitespace to focus on meaningful changes.
Good to know
Added lines are marked with a bold left bar and a plus; removed lines are struck through with a lighter bar and a minus; unchanged lines stay muted for context. Because nothing is uploaded, you can safely compare private contracts, code, or notes.
Frequently asked questions
How does the text diff checker work?
Paste your original text on the left and the changed version on the right. The tool compares them line by line using a longest-common-subsequence algorithm and highlights which lines were added and which were removed, with line numbers for each side.
Is this diff checker free?
Yes — it's a completely free online text diff tool with no sign-up and no limits. Everything runs in your browser.
Is my text uploaded to a server?
No. The comparison happens entirely in your browser with no upload, so even confidential documents, code, or contracts stay private on your device.
Can it ignore case or whitespace differences?
Yes. Turn on "Ignore case" to treat upper and lower case as equal, and "Ignore whitespace" to ignore leading and trailing spaces on each line. Useful for comparing reformatted text or code.
Does it compare word by word or line by line?
It compares line by line, which is the most reliable way to spot changes in documents, lists, configuration files, and code. Each changed line shows up as a removed line plus an added line.
What can I use it for?
Comparing two drafts of an article, spotting changes between code versions, checking edits to a contract, diffing config files, or finding what changed between two exports — anything where you need to see line-by-line differences quickly.
Why are some lines shown as both removed and added?
When a line is edited rather than purely inserted or deleted, the diff shows the old version as removed and the new version as added. That keeps the comparison exact and easy to read.
Learn more
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