Text Diff Checker
Compare two texts and see the differences highlighted line by line.
Compare two versions of text instantly
The Text Diff Checker compares two blocks of text and highlights exactly what changed between them, line by line. Paste an original version on the left and a modified version on the right, and the tool shows which lines were added (in green with a plus sign), which were removed (in red with a minus sign), and which stayed the same. It is built for writers reviewing edits, developers comparing snippets of code or configuration, and anyone who needs to spot the difference between two drafts of a document.
Under the hood the tool uses a longest common subsequence (LCS) algorithm. Instead of comparing the two texts character by character, it finds the longest sequence of lines that both versions share and treats everything else as an insertion or deletion. This produces a clean, readable result that follows the same logic used by version-control tools like Git, so the changes line up the way you would expect.
How to use the diff checker
Paste or type your original text into the left box and the updated text into the right box. Click the Compare button and the result appears below, with a summary count of how many lines were added, removed, and left unchanged. Each differing line is colour-coded so you can scan the changes at a glance, and long lines wrap rather than being cut off.
Because the comparison works at the line level, splitting your content into one sentence or one logical unit per line will give you the most precise results. If two paragraphs differ by only a few words but sit on a single line, the whole line will be marked as changed rather than the individual words.
Privacy and practical notes
Everything runs entirely inside your browser. Your text is never uploaded to a server, stored, or shared, which makes the tool safe for comparing confidential drafts, private notes, or proprietary code. Nothing leaves your device, and closing the tab clears the data.
There is no length limit other than your browser's available memory, so you can compare anything from a couple of lines to long documents. The tool is completely free, requires no sign-up, and works on both desktop and mobile browsers.