Code Diff Checker — Free · All Languages · Myers · Patience · Histogram
Real-time diff · Character-level · AI summary · Merge mode · Timeline · Git export · 100% browser
Free online code diff checker with three diff algorithms, character-level highlighting, file upload, URL import, and AI-powered change summaries. Works with 10+ programming languages — auto-detected.
What is a Code Diff Checker?
A diff checker compares two versions of text or code and highlights what changed. It shows added lines in green, removed lines in red, and changed lines in amber — exactly like git diff or a pull request review on GitHub.
Key Features
This tool includes side-by-side and inline views, character-level diff highlighting (exact words that changed), three diff algorithms (Myers, Patience, Histogram), AI-powered plain English summaries, 3-way merge mode, change timeline, and multiple export formats including .diff (git patch) and HTML reports.
Frequently Asked Questions
What is the Patience diff algorithm?
Patience diff was created by Bram Cohen (creator of BitTorrent). It finds unique lines first and uses them as anchors, producing more readable diffs for code that has been reorganized or refactored.
What is the Histogram algorithm?
Histogram diff (used by JGit/Eclipse) extends patience diff to better handle code with repeated similar patterns like getter/setter methods or boilerplate code. Often produces cleaner diffs for Java and verbose languages.