Compare two texts

Word by word or line by line?

The two modes answer different questions. Word by word reads each text as a sequence of words and finds the smallest set of words to remove and add to turn one into the other. Where the lines happen to break doesn’t matter, which is what you want for prose that was re-wrapped, pasted from an email or reflowed by a word processor. Line by line compares whole lines first, then marks the words that changed inside each changed line. It suits text where every line is a unit of its own: lists, addresses, subtitles, song lyrics, spreadsheet rows or settings files. Here is what each mode reports for a few typical edits:

With Ignore case turned on, the last example becomes “No differences”. The ignore options never change your text, only what counts as a difference.

Essays, drafts and feedback

Writers compare drafts to see what an editor, a teacher or a co-author actually changed when the document came back without tracked changes. Paste your version on the left and theirs on the right, keep word mode on, and step through the edits with Next change. Students use the same trick to check that a revision really addressed the comments, and to confirm a final copy matches the version that was approved.

Contracts and other documents where every word counts

In an agreement, a changed date, amount or “not” matters more than a whole rewritten paragraph of boilerplate. Comparing the version you agreed to with the one sent for signature shows quiet edits such as 30 days becoming 15, or a clause that disappeared. Turn on Ignore punctuation only if you are sure commas don’t matter: in a contract they sometimes do. Because the comparison runs on your device, confidential documents never leave it. A comparison is a reading aid, not legal advice; have anything important reviewed by a professional.

Comparing without code

Programmers have diff tools built into their editors, but the same idea helps with everyday text: two versions of a mailing list, an exported report from this month and last, a product description before and after an update, or two sets of meeting notes. Line mode with line numbers makes it easy to find each change in the original file. To clean a list before comparing it, sort it with alphabetical order or strip repeats with remove duplicate lines, so the comparison shows real differences rather than reordering. For text pasted from a PDF, fix the broken lines first with remove line breaks, and keep drafts between visits in the online notepad.