Free Online Diff Checker & Text Compare

Paste the original into the left box and the new version into the right box, then click Compare. Removed lines show in red, added lines in green, and a counter shows how many lines were added, removed and unchanged.

It uses the line diff from the jsdiff library, which is based on the Myers algorithm, the same default method Git uses. It finds the smallest set of removed and added lines that turns the original into the modified text.

No, not yet. A trailing space, a tab in place of spaces or a capital letter makes the line count as changed. Clean both texts first, for example by trimming trailing spaces in your code editor, then compare them.

Something changed on every line, often something you can't see. Re-indenting with tabs, trailing spaces added by an editor, or text wrapped at a new width all count. Minified code is one long line, so format both sides first.

When the original's last line has no line break after it, adding a line below changes that line's ending, so it shows as removed and added again. Press Enter at the end of both texts to avoid it.

No. The checker marks whole lines, so a one-word edit shows the full line as removed and then added. For long paragraphs, put each sentence on its own line in both texts so the changed sentence stands out.

Split view shows the original on the left and the modified text on the right, with changes shaded. Inline view shows one column with a minus or plus before each changed block. The split columns are not lined up row by row, so inline reads better for long diffs.

There is no set limit, but large and very different texts are slow. In a Node test of the same code, 100,000 lines with 1% changed took 0.3 seconds, while 5,000 lines that all differed took about 3 seconds. The page waits while it runs.

Only as pasted text. There is no file upload, so open each file, copy its text and paste it in. Binary files such as images can't be compared; for a PDF, copy its text out first.

Not as a real patch. Copy Diff gives plain text with a minus or plus before changed lines, with no @@ headers, so git apply can't read it. Blank lines are left out of the copy, which matters where spacing counts.

Yes. The comparison runs in your browser and neither text is sent. On the live site, Google Analytics gets a page view, the time a compare took and a note when you copy or clear, but nothing you paste.