Compare and Diff Dart Code Online

Why Use DiffMergy’s Code Compare & Diff?

Whether you are reviewing a pull request, debugging a regression, or auditing a codebase migration, DiffMergy’s Code Compare gives you a precise, color-coded view of every change between two code versions. With 30+ language modes, word-level diff highlighting, and an intuitive accept/reject workflow, it is the fastest way to understand what changed without leaving your browser.

Unlike cloud-based alternatives, all comparison logic runs locally using a custom diff engine optimized for accuracy. There are no file size limits, no upload queues, and no privacy concerns. Simply paste your code and see the diff instantly.

Key Features

• Real CodeMirror 6 editor with line numbers, code folding, bracket matching, auto-indent, and multi-cursor editing
• Side-by-side and unified diff views with word-level change highlighting inside the editor
• Three-way merge (base, ours, theirs) with conflict markers and one-click conflict resolution
• Command palette (Ctrl+K) for keyboard-first navigation across every tool
• Accept or reject individual changes with full undo/redo history
• Automatic move detection for refactored or relocated code blocks
• Handles very large files with virtualized diff rendering
• 30+ programming languages with syntax highlighting
• Compare by pasting, uploading files, or fetching a URL
• Share comparisons via compressed link, export unified .patch files, and save sessions locally

100% Private — No Server Upload

All processing happens entirely in your browser using modern browser APIs. Your sensitive source code, credentials, and files never leave your device — no servers, no databases, no tracking, no sign-up required.

Fast & Reliable

Built with vanilla TypeScript and a lightweight custom engine, DiffMergy delivers sub-millisecond processing with zero network latency. The entire toolkit works on any modern browser across all operating systems, with no installation or setup needed.