Text Diff Checker
Compare two texts line by line and highlight added and removed lines.
About this tool
Compare two texts line by line and highlight added and removed lines. Your data never leaves your browser. Client-side processing with zero waiting. No accounts, no paywalls, no watermarks.
How to use
- 1
Type or paste your data in the input box
- 2
Choose your options and run the tool
- 3
Copy or download the result — done!
Frequently asked questions
▸How does the comparison work?
It computes a line-by-line diff using the longest common subsequence. Lines only in the left text are marked removed, lines only in the right are marked added, and unchanged lines stay neutral.
▸Is my content uploaded anywhere?
No. Both texts are compared inside your browser with plain JavaScript — nothing is sent to any server, so it is safe for private drafts and internal code.
▸How large can the texts be?
Each side accepts up to 1,500 lines. Larger inputs are rejected with a clear message so the page never freezes; for big documents, split them into sections first.