Diff Checker Online - Free diff checker to compare texts and highlight differences.
Free online diff checker. Compare two texts side by side with highlighted changes. Great for reviewing code and document edits.
How to Use Diff Checker
- 1Paste the original text on the left.
- 2Paste the modified text on the right.
- 3Click "Compare" to see the differences highlighted.
Frequently Asked Questions
What is a diff?
A diff (difference) shows the changes between two versions of text. Additions are typically highlighted in green and deletions in red.
Does it work with code?
Yes. You can compare any plain text including source code, configuration files, JSON, and more.
Is there a size limit?
There is no strict limit, but very large texts (over 100KB) may slow down the comparison in your browser.
Found a bug or have a suggestion? Report it on GitHub
Learn More
Guide
Text Comparison Guide
How diff tools work.
GuideDiff Algorithms Explained
Myers, patience, and histogram.
GuideCode Review Diff Tips
Spot bugs faster in diff views.
GuideVisual Diff Tools for Non-Developers: Compare Anything
Learn how visual diff tools help non-developers compare documents, contracts, sp
GuideComparing API Responses: Find Differences Fast
Learn how to compare API responses effectively to catch regressions, validate in
GuideUsing Diff Tools in QA Testing
How QA teams use text comparison to verify regression, API responses, and config
GuideUnified Diff Format Explained
Read and interpret unified diff output — the standard format used by Git and pat