Find the differences between two texts

Why compare two versions of a document?

Checking two versions of a contract, a résumé or an article by eye is slow and unreliable: a changed date, an added "not" or a different amount is easy to miss. A text compare tool, also called a diff checker, lines up the two versions automatically and highlights every difference. Typical uses: seeing the edits a proofreader made without track changes, checking that a contract sent back for signature is identical to the one you approved, spotting what changed between two versions of a script or a config file, or comparing a text before and after running it through a grammar checker or an AI.

Lines, words or characters: which mode should you use?

Line mode compares each line as a block: if a single character changes, the whole line shows as deleted and then added. It's the natural mode for code, a pasted table or a list. Word mode is the easiest to read for written text: if "the rent is $1,850" becomes "the rent is $1,880", only the amount is highlighted. Character mode goes even further and shows a changed letter or punctuation mark, for example "their" turned into "there". It's very precise but quickly gets cluttered on a heavily rewritten text: start with words, then zoom in if needed.

Avoiding false differences

Text copied from a PDF, an email or a word processor often contains extra spaces or changed capitalization. Without precautions, the tool then flags dozens of differences that aren't really changes. Turn on the option that ignores whitespace so extra spaces no longer count, and the one that ignores case so that "London" and "LONDON" are treated as identical. Be careful: in code, case and spacing can change the meaning (in Python, indentation is part of the program), so leave these options off. To tidy up a text before comparing it, "Case Converter" converts a whole text in one click, and "Word Counter" gives you its exact length.