What is a Text Diff Checker?
A text diff checker compares two versions of text and highlights the differences between them — showing additions in green and deletions in red, line by line. "Diff" (short for "difference") is a computing concept that originated in Unix systems in the 1970s and is now fundamental to version control systems like Git, code review platforms like GitHub, and document collaboration tools like Google Docs.
Writers use text diff tools to compare manuscript revisions, find changes made by editors, or verify that a translation matches the original. Developers use diff to review code changes before committing, compare configuration files between environments, or audit security-sensitive text. Content managers use it to compare website copy versions. Our tool provides line-by-line diff with a count of additions and deletions, making it easy to see exactly what changed between two versions of any text.
How to Use the Text Diff Checker
- Paste the Original Text into the left panel.
- Paste the Changed Text into the right panel.
- Click Compare Texts.
- Review the diff result — green lines (prefixed with +) were added, red lines (prefixed with −) were removed, and grey lines are unchanged.
Why Use Our Text Diff Checker?
- 100% Free — Compare unlimited text pairs at no cost.
- No Registration — No sign-up required.
- Browser-Based — Text is compared locally in your browser — never sent to a server.
- Colour-Coded Output — Additions in green, deletions in red, unchanged text in grey for instant visual clarity.
- Change Summary — Shows total additions and deletions count at the top of the diff result.
Frequently Asked Questions
The tool splits both texts into arrays of lines and compares them position by position. Lines that are identical in both versions are shown in grey. Lines that exist only in the original (left) are shown in red with a "−" prefix. Lines that exist only in the modified (right) version are shown in green with a "+" prefix. This produces a simple line-level diff.
This tool performs line-level diff — if any part of a line changes, the entire line is shown as changed. Word-level or character-level diff (highlighting only the specific words that changed within a line) is more complex and requires algorithms like Myers Diff or the Longest Common Subsequence algorithm. For detailed word-level diff, use tools like diff2html or VS Code's built-in diff viewer.
Yes, for quick comparisons. Paste two versions of your code and see which lines changed. For serious code review and version control workflows, use Git's built-in diff ("git diff"), GitHub's pull request diff view, or an IDE like VS Code which shows inline diff with full syntax highlighting. This tool is best for quick text comparisons without a development environment.
Yes. Text comparison happens entirely in your browser using JavaScript string operations. Neither version of your text is sent to any server. This makes the tool safe to use with confidential content such as legal contracts, proprietary code, medical records, or sensitive business documents — close the tab when done and the data is gone.