Frequently asked questions
- Is my data uploaded to a server?
- No. Every operation runs inside your browser using JavaScript. Nothing you paste or type is sent to our servers, stored or logged. You can disconnect from the network after the page loads and the tool keeps working.
- Why does it not report every line as changed when I paste from Windows?
- Because line endings are normalised before comparing. Text copied from Windows carries carriage returns that text from a terminal does not, and a diff that treats that as a change on every line is useless.
- How does it decide which lines match?
- By longest common subsequence, the same idea behind the diff command. It finds the largest set of lines that appear in both, in order, and reports everything else as an insertion or a deletion.
- Can it compare JSON?
- It can, but the JSON diff compares structure rather than text, so it ignores key order and formatting and tells you what actually changed in the data.
Related tools
Stuck on an error?
Every common JSON parse error is explained separately, with the cause and the fix: common JSON errors.
How your data is handled
Everything happens on your device. There is no upload, no storage and no logging, and only your interface preferences - theme, indentation, font size and word wrap - are kept between visits. Closing the tab clears the document.