Paste two versions of anything and see what changed. Both panes accept a dropped file. The documents people most need to diff — a contract, a config with credentials in it, a customer export — are precisely the ones that should not be uploaded to compare.
Choosing the granularity
Line is right for code, config files and data. It is how git diff works and it is fast on large inputs.
Word is right for prose. A reworded sentence shows as one line changed at line granularity, which tells you nothing; word granularity highlights the actual edit.
Character is for the cases where a single character is the difference — a changed digit in an identifier, a swapped operator, a homoglyph. It is the slowest and the noisiest, so reach for it last.
Line endings and invisible differences
If you specifically need to find whitespace differences — you are debugging a YAML file, or a checksum mismatch — turn off "Ignore trailing whitespace" and switch to character granularity.
Diffing JSON usefully
Other names for this
Also searched as “text compare”, “compare two files”, “text difference checker”.
Questions
- Can I compare two files rather than pasting?
- Yes. Each pane accepts a dropped file, and the file never leaves your machine.
- The two texts look identical but it shows differences.
- Usually invisible characters — a non-breaking space, a zero-width space, or a different Unicode dash. Switch to character granularity to find them.
- How large can the inputs be?
- Line granularity handles files of several megabytes comfortably. Character granularity is quadratic in the worst case and gets slow well before that.
- Does my text leave the browser?
- No. Everything runs as JavaScript in this tab — there is no server involved and no request is made. Open the Network panel and watch, or turn your Wi-Fi off and keep using the tool.