About the Diff Checker
Paste an original and a changed version of any text — a contract, an essay, a config file or a piece of code — and the diff checker shows exactly what changed. Removed lines are highlighted in red, added lines in green, and inside a modified line the changed words are marked so you do not have to hunt for a single comma.
Switch between a side-by-side and a unified view, ignore differences in case or whitespace, and hide the unchanged parts of long documents. The comparison runs entirely in your browser, so confidential text never leaves your device.
How to use the Diff Checker
- Paste the first version into “Original text” and the second into “Changed text”.
- Differences appear instantly, with the number of lines added and removed.
- Choose “Side by side” or “Unified”, and tick “Ignore whitespace” or “Ignore case” if those changes do not matter.
- Tick “Show only changes” to collapse unchanged lines in long texts.
Frequently asked questions
How does the diff checker find differences?
It uses the Myers diff algorithm — the same approach as Git — to find the smallest set of lines to add and remove that turns the original into the changed text. Lines that were edited are then compared word by word to highlight the exact change.
What does “Ignore whitespace” do?
It treats lines as equal when they differ only in leading or trailing spaces, or in the number of spaces and tabs between words. This is useful when comparing code that was re-indented.
Is there a size limit?
Texts of several thousand lines compare in well under a second. For very long texts, only the first 10,000 lines of each side are compared.
Is my text uploaded anywhere?
No. The comparison runs in your browser and nothing is sent to a server, so it is safe for contracts, private documents and source code.