Code Diff Checker — Side-by-Side · Char-Level · AI Review · Merge Mode
Real-time diff · Character-level · AI summary · Merge mode · Timeline · Git export · 100% browser
Compare two versions of code side-by-side with real-time highlighting. Character-level diff shows exact words that changed, not just whole lines. AI summary explains changes in plain English. Export as git .diff patch or HTML report. Supports JavaScript, Python, HTML, CSS, SQL, JSON, Rust, PHP and more — 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 character-level diff?
Character-level diff (also called word diff or inline diff) highlights the exact characters or words that changed within a modified line. Instead of highlighting the entire changed line, only "John" being replaced by "Jane" would be highlighted.
Which diff algorithm should I choose?
Myers (default) is the standard algorithm used by git — best for most cases. Patience is better when code has been refactored and moved around — it finds more meaningful diff boundaries. Histogram is similar to patience but handles repeated elements better.
What is the Change Timeline?
The Change Timeline lets you save snapshots of each diff (v1, v2, v3...). Click "Save Version" to capture the current state. The timeline shows stats (+added -removed ~changed) for each version and lets you reload any past comparison.
Can I compare code from GitHub?
Yes. Paste any raw GitHub URL (raw.githubusercontent.com) or GitHub Gist URL in the URL import field. The tool fetches the file content and loads it into the panel automatically.
What is Merge Mode?
Merge Mode provides 3 input panels: Base (common ancestor), Left (your version), Right (their version). This simulates a git 3-way merge, showing conflicts between your version and their version relative to the base.
What export formats are available?
Three formats: (1) .diff — standard git patch format, can be applied with git apply. (2) HTML Report — colored side-by-side HTML file for sharing. (3) Unified Diff — copied to clipboard in unified diff format (+/-/ lines).