Text Compare and Diff Checker

Paste the original text into the first box and the new version into the second. The differences appear below as you type: removed lines on a red background, added lines on a green one, and the changed words marked more strongly inside them. The summary above the result counts the lines removed and added, and the arrows beside it jump to the previous or next change, which helps in a long document. If you pasted the texts the wrong way round, press Swap.

Word highlighting, the default, marks whole words that changed, which reads best for prose: "brown" becomes "red". Character highlighting marks only the characters that differ, which is what you want for codes, numbers and identifiers, where a single transposed digit such as INV-0431 against INV-0413 is the whole change. You can switch between them in the settings at any time.

Ignore case treats "Apple" and "apple" as the same, so a change in capitalization is not reported. Ignore whitespace leaves spaces and tabs out of the comparison, so re-indented code or text with doubled spaces shows only its real changes. Ignore blank lines leaves empty lines out, which helps when one copy of a document has a blank line between paragraphs and the other does not; the line numbers still count them. Line endings from Windows and Mac are always treated as the same.

It is the share of the two texts that is the same, counted in characters with spaces left out: twice the characters they have in common, divided by the characters in both. A long document with a few words changed scores close to 100%, and two unrelated texts close to 0%. It is rounded down, so texts with any difference never show 100%. It measures how much text changed, not whether one text was copied from the other.

No. The texts are compared by a script running in your browser, and files you open are read on your device. Nothing you paste or open is sent to a server or stored, and the page keeps working if you go offline after it has loaded.

Yes. Press Open file under either box, or drag a file onto it, to load the text of a .docx, .odt, .pdf, .xlsx or .pptx file, or any plain text file such as .txt, .csv, .json or source code. Only the text is compared, not fonts or layout. A scanned PDF has no text to read; use the Image to Text Converter on it first. Older .doc and .xls files need saving as .docx or .xlsx.

Text Compare follows the order of the lines, which suits two versions of a document. For two lists where the order does not matter, such as email addresses, names or product codes, use Compare Two Lists, which shows the items only in the first list, only in the second, and in both.

It uses the Myers difference algorithm, the method behind the diff and git diff commands, which finds the smallest set of lines to remove and add to turn the original into the changed text. The removed and added lines of each change are then compared again word by word or character by character to mark exactly what changed. Copy gives the result as plain text, with each removed line starting with a minus sign and each added line with a plus sign.