Paste two texts to instantly see what changed. Line-by-line or word-by-word diff. No data leaves your browser.
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Diff Output
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Paste text in both panels above, then click Compare
▶Paste your original text in the left panel
▶Paste your modified text in the right panel
▶Click Compare or wait for auto-diff
What Is a Text Diff Tool and When Do You Need One?
A text diff tool compares two pieces of text and highlights exactly what has changed between them — additions shown in green, deletions shown in red, and unchanged content left neutral. The concept comes from software development, where comparing different versions of source code is an everyday necessity. But diff tools are now invaluable far beyond programming: editors comparing manuscript drafts, lawyers reviewing contract redlines, translators checking updated source documents, and students tracking revisions in collaborative essays all benefit from instant, visual difference detection.
Consider a practical example: a client sends you a revised contract and says "we made a few changes." Without a diff tool, you are left reading every paragraph searching for what shifted. With a text diff tool, you paste both versions and within seconds every altered clause is highlighted in unmistakable color. The same applies to code review — even if your team uses GitHub pull requests, sometimes you need to quickly compare a snippet from a colleague's Slack message against what is already in production. Pasting both into a diff tool gives you the answer instantly, without opening a terminal or creating a branch.
Frequently Asked Questions
How does the comparison work?
This tool uses the industry-standard Longest Common Subsequence (LCS) algorithm via the open-source jsdiff library. In line mode, the algorithm finds the longest sequence of lines that appear in both texts in the same order, then marks everything else as added or removed. The result closely mirrors what professional tools like Git's git diff produce. In word mode, the same algorithm operates at the word level within each line, making it ideal for catching small prose edits like a changed preposition or a rephrased clause.
Is my text uploaded to a server?
Absolutely not. This is a 100% client-side tool. All diffing is performed by the jsdiff JavaScript library running directly inside your browser. Your text never touches our servers — there is no backend, no API call, no logging. This makes the tool safe for confidential content: legal contracts, private correspondence, proprietary code, or any sensitive document you would not want stored on a third-party server. You can even disconnect from the internet after the page loads and the tool will continue to work perfectly.
What is the difference between line mode and word mode?
Line mode treats each line as an atomic unit. If even one character in a line changes, the entire line is marked removed (old version) and added (new version). This is the standard diff view used by Git and most developer tools — ideal for code, configuration files, or any content where line structure is meaningful.
Word mode operates at the word level within lines, highlighting only the individual words that changed inline. This is far more useful for prose documents — a paragraph where only two words were rephrased will show just those words highlighted rather than marking the whole paragraph as changed. Use line mode for code and structured data; use word mode for articles, contracts, and natural language text.
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