Guide
How to compare texts effectively
A diff checker shows exactly what changed between two versions of a text: which lines were added, removed or edited. It's useful for reviewing contract revisions, checking what an editor changed in an article, comparing configuration files, or finding the one line that broke your code.
How the comparison works
The tool uses the Longest Common Subsequence (LCS) algorithm, the same family of algorithms used by Git and other version-control tools. It finds the largest set of lines the two texts share, in order, and marks everything else as an addition or a deletion. The result is the smallest set of changes that turns the original into the new version.
Split view vs unified view
- Split view puts the original and changed texts side by side. It's the easiest way to read through edits to prose or documents.
- Unified view shows a single column, with removed lines marked − and added lines marked +, like a Git diff. It's compact and familiar for reviewing code.
Tips for cleaner comparisons
- Paste plain text. Text copied from Word or PDFs may contain different line breaks or invisible characters that show up as changes.
- If a whole paragraph shows as changed, check for differences in line wrapping. Re-wrapped text is a different line to a diff tool.
- Trailing spaces and tab-versus-space indentation count as changes. Normalise them first if they don't matter to you.
- For code, open the files directly with the file buttons to avoid copy-paste formatting problems.
Private by design
Comparisons run entirely in your browser. Nothing you paste is sent to a server or stored, so it's safe for contracts, credentials in config files, and unpublished writing.