Difference Checker — Compare Text Online
Paste two versions of anything — code, logs, CSV, prose — and see exactly what changed, line by line and word by word.
How to compare two text files online
- Paste the original version into the left box and the changed version into the right.
- Press Find Difference. The checker aligns the two versions and marks every added, removed and changed line. (Prefer it to update as you type? Turn on Real-time editor in the left panel.)
- Inside a changed line, the exact words that differ are highlighted, so you are not left comparing two long lines by eye.
- Use Previous and Next to step through the changes, or Merge to copy one side's version of a change into the other.
Smart, word and character precision — what each one shows
Smart compares line by line, then highlights the changed words within a line. It is the right answer almost always, and it is the default. Word compares by word throughout, which suits prose that has been reflowed — where the line breaks moved but the sentences did not. Character compares letter by letter inside a changed line, which is how you find a single altered digit, a swapped letter or a stray trailing space.
Split view or unified view
Split puts the two versions side by side, which is easier when whole blocks moved or when
you want to read both versions of a line at once. Unified stacks them into a single
column with - and + markers, the way git diff
prints, which is easier to copy into a review comment and easier to read on a phone.
What happens to the text you paste
The comparison itself runs entirely in your browser. Your text is not uploaded, not stored and not logged, and the tool works with the network disconnected. Two buttons are the exception, and both are opt-in: Share stores the two sides on our servers so that a link can be opened by someone else, and Explain sends them to an AI model to be described. Each says exactly what it will do before it does it, and neither runs unless you press it.
Difference checker, diff checker, text compare — the same thing
These are all names for one tool. Developers tend to say diff, after the Unix command that has printed differences since 1974; everyone else says difference or simply compare. Whichever you searched for, this page does it: comparing two blocks of text and showing what changed. It handles code, configuration, logs, CSV, query results, JSON, YAML, markdown and plain prose — anything you can paste as text. It does not compare images, PDFs, spreadsheets or folders.
Frequently asked questions
Is there a size limit? Not for the comparison — it is bounded only by your browser's memory, and a nine thousand line file compares in well under a second. Shareable links are capped, and the page tells you the number.
Do I need an account? No. Nothing on this page requires signing in.
Comparing JSON? Use the JSON Diff instead — it compares by structure rather than by line, so two documents that differ only in key order come out identical rather than as pages of noise.
Why is a changed line shown as one row rather than a removal and an addition? Because that is what happened. Pairing them is what makes a side-by-side readable.