How to use
- Paste or type the original text on the left and the changed text on the right. Use Load example to try it.
- Choose Side by side or Unified, and turn on Ignore whitespace or Ignore case if small formatting differences are not relevant.
- Read the highlights and the summary, and use Previous and Next change to jump between differences.
Examples
Original: apple, banana, cherry (one per line). Changed: apple, blueberry, cherry, date.
→ 2 changes: +2 added lines, -1 removed linebanana was replaced by blueberry, and date was added at the end.
Original: Hello. Changed: hello. Ignore case turned on.
→ 0 changes: the texts are identical with the current options
Original: a b (two spaces). Changed: a b (one space). Ignore whitespace turned on.
→ 0 changesSpaces, tabs and carriage returns are ignored, but line breaks still count.
How it works
The tool compares the two texts line by line, groups neighbouring differing lines into blocks, and then compares the characters inside each block so that only the parts that actually changed are highlighted. Red marks text that is only in the original, and green marks text that is only in the changed version.
The comparison uses the open-source CodeMirror editor and its merge extension, running entirely in your browser.
Ignore whitespace and Ignore case work by comparing a simplified copy of each text (without spaces and tabs, or in lower case) and then mapping the differences back to the text you entered, so the highlights always point at your original characters.
Sources
Frequently asked questions
- What is the difference between side by side and unified view?
- Side by side shows the original and the changed text in two columns, which is easy to scan on a wide screen. Unified shows one column with removed and added lines together, which fits narrow screens. In unified view the original is read-only, so switch to side by side to edit it.
- What does Ignore whitespace do?
- It treats spaces, tabs and carriage returns as if they were not there when comparing. Line breaks are still compared, so moving text to another line is still reported as a change.
- Can I compare large files?
- Yes, within what your browser can handle. For very large or very different inputs the comparison may switch to a faster, less precise method, so changed characters inside a line may be highlighted more coarsely.
- Is my text uploaded?
- No. The comparison runs in your browser and the text is never sent to a server.
- How are lines counted in the summary?
- Added lines are lines that exist only in the changed text, and removed lines exist only in the original. A changed line counts as one removed and one added line. A change is a block of neighbouring differing lines.