Diff Checker
Compare two text blocks and see the differences highlighted line-by-line. All comparison runs locally.
About this tool
The Diff Checker compares two blocks of text line by line and highlights the differences with color coding. Lines that exist in the original (left) but not in the modified (right) are marked in red as deletions. Lines that were added in the modified version appear in green as additions. Unchanged lines remain unhighlighted. This is the same fundamental algorithm used by Git and other version control systems when you run git diff.
Use cases range from comparing code snippets before committing, reviewing edited documents or contracts, verifying that changes match what you intended, to comparing configuration files between environments. All processing runs locally in your browser — your text never leaves your device.
How to use
- Paste the original text in the left panel. This is your "before" version — the baseline for comparison.
- Paste the modified text in the right panel. This is your "after" version — what you want to compare against the original.
- Review the diff. The output panel below shows line-by-line differences with color highlighting. Red lines were removed from the original, green lines were added in the modified, and unmarked lines are identical.
Frequently asked questions
What is a diff and how does it work?
A diff compares two texts line by line and highlights additions (green), deletions (red), and unchanged lines. It's the same algorithm used by Git and code review tools to show what changed between two versions of a file.
What can I use a diff checker for?
Comparing code versions, reviewing edited documents or contracts, verifying configuration file changes between environments, and checking draft revisions of articles.
Is my text stored or shared?
No. All comparison happens locally in your browser. The text you paste never leaves your device and is never stored or transmitted to any server.
Does this work on mobile?
Yes. The Diff Checker is fully responsive and works on all modern browsers including iOS Safari and Android Chrome.