Galley proof · marked in red
Diff Checker
Paste the original and the revised copy. The proof is set from the original and marked the way a proofreader marks it: struck-through words with a dele in the margin, a caret where words go in, and the inserted words written beside the line.
How to read the marks
A galley proof is the long, unpaginated print a typesetter pulled so the proofreader could mark corrections before the pages were made up. The marks are a small standard language, still used today (ISO 5776 and the Chicago Manual of Style both list them). This page uses the three that matter for a comparison: a word to remove is struck through in the text and answered with a dele (a looped d) in the margin; a place where words go in gets a caret in the text, with the new words written in the margin and closed with a slash; when a whole line is new it is written in place in red so it stays readable.
What is compared
Lines first, then words inside the lines that changed. Two copies with only a comma moved will show that comma and nothing else. Ignore case treats Fox and fox as the same word; ignore spaces trims each line before comparing so re-indented code does not light up the whole proof.
Does it show character-level differences?
Word level. A changed letter marks the whole word, which is how a proofreader works: the word is struck and the corrected word goes in the margin.
Can I compare two files?
Paste them. Anything up to a few thousand lines compares in a moment in your browser; nothing is uploaded.
What is a unified diff?
The plain-text format git and patch use: a header, then every line prefixed with a space (unchanged), minus (removed) or plus (added). The copy button gives you one for pasting into a review or a commit message.