Paste two versions of a text and see exactly what changed: line by line, word by word, entirely in your browser.
How it works
The tool aligns the two texts on their longest common sequence of lines, the same technique developer diff tools use. Identical lines stay plain; changed lines are shown as amber pairs with the differing words marked inline; additions are green and removals red, each with its own line number per side.
Everything runs locally. Your texts are never uploaded, and there is no signup. This compares the two texts you paste; it is not a web plagiarism scan.
Frequently asked questions
How does the text compare tool work?
Paste your original text on the left and the changed version on the right, then click Compare. The two texts are aligned line by line, and lines that were changed, added, or removed are color-coded. Inside changed lines, the exact words that differ are highlighted too.
What do the colors mean?
Amber rows were changed (the line exists in both versions but differs; the differing words are marked inline). Green rows were added in the new text, and red rows were removed from the original. Uncolored rows are identical.
Does it detect moved text?
The comparison finds the longest common sequence of lines, so a block that moved shows up as removed in one place and added in the other, which is also how developer diff tools present moves. Reordered words inside a line are marked as changed words.
Is this a plagiarism checker?
No. It compares exactly the two texts you paste, nothing is checked against the web. For a similarity score between two texts, our Text Similarity Checker gives a percentage; for web-scale plagiarism detection you need a crawling service.
How large can the texts be?
Comfortably thousands of lines. Identical beginnings and endings are skipped instantly, and only the differing middle is deeply compared. For extremely large, completely different texts the tool falls back to showing one removed and one added block rather than freezing your browser.
Are line breaks and spaces significant?
Yes. Lines are compared exactly as written, including spacing, because in code, CSV data, and legal text those differences matter. If you only care about wording, normalize the texts first (for example with our Case Converter).
Is my text uploaded anywhere?
No. The comparison runs entirely in your browser; nothing is sent to a server and there is no signup. Your latest texts are remembered only in your own browser.