Try the free tool below. It runs in your browser, with no sign-up and no download.
What Is the Text Diff Checker?
When two versions of a text look almost the same, the difference can be hard to spot by eye. Our text diff checker compares two texts and marks every addition in green and every removal in red. Unchanged text stays plain, so your eye goes straight to what changed.
The comparison uses the diff library in your browser, and it works line by line or word by word. It also counts added, removed, and unchanged characters, which gives you a quick sense of how large a change is. Nothing you paste leaves your device.
How to Use It
Paste the first version on the left and the second on the right, then press Compare. The result shows the full merged text with changes marked in place, so you can read the new version with its edits visible. Line mode is best when whole sentences were added or removed. Word mode is best when only a few words inside a sentence changed.
Try the sample to see it in action. One verb changes, one word is added at the end, and both edits are marked at once.
When Is It Useful?
Use it to review an edited essay, article, or report, and to check what a colleague changed in a document. Use it to compare two versions of a letter, a contract draft, or a set of instructions, where one changed word can change the meaning. Use it for study too: comparing your answer with a model answer shows exactly where they differ.
Writers use diffs to review revisions without re-reading the whole text. Editors use them to confirm that requested changes were made and that nothing else changed by accident.
Tips for Clear Results
Keep line breaks the same in both versions when you can. If one version wraps lines differently, line mode may mark many lines as changed even though the words are the same. In that case, switch to word mode, which ignores line breaks and marks only the changed words.
For long texts, compare one section at a time. Short, focused diffs are easier to read and easier to act on than one giant diff.
Frequently Asked Questions
Is my text sent to a server? No. The comparison runs in your browser.
What is the difference between line and word mode? Line mode marks whole changed lines. Word mode marks changed words only.
Can it compare code? Yes. It compares any plain text, including code, though it marks text changes rather than code meaning.
Can I save the result? Copy the marked result from the page, or take a screenshot of the comparison.
Using Diffs to Improve Your Writing
A diff is not only a review tool; it is a learning tool for writers. Take a paragraph you wrote, rewrite it from scratch without looking at the original, and diff the two versions. The marked changes show which phrases you naturally repeat, which words you swap for stronger ones, and which sentences you always shorten. Writers are often surprised by how much stays the same, which shows their voice, and by which habits change, which shows where they are growing. Teachers can use the same trick: ask a student to revise an essay, then diff the draft and the revision together in class. The class sees exactly what revision means in practice, not as an abstract instruction but as marked lines on a page. Revision stops being a vague demand to do better and becomes a visible set of choices: a word cut here, a sentence reordered there, a vague claim replaced by a concrete one. Over time, students who watch their own diffs start to revise more boldly, because they can see that changing text is normal and safe.
Try diffing your first draft against your final draft for your next piece of writing. The pattern of your edits is a personal map of your writing habits, and it is more honest than any advice about writing in general.
Also in Spanish
This tool is also available in Spanish: Comparar dos Textos Online Gratis – Ve Diferencias LÃnea por LÃnea.