File Diff Tools — Libor Benes (Dr. B)

File Diff Tools is a lightweight Firefox sidebar extension offering efficient offline access to 118 essential file diff utilities, options, output formats, and practical usage scenarios.

The diff command, written by Douglas McIlroy and James Hunt at Bell Labs, appeared in Version 5 Unix in 1974. It is an abbreviation of "difference," indicating its operation of finding and displaying differences between files. The algorithm was refined over decades, with the current efficient algorithm designed by Eugene W. Myers in the 1980s. The tool has become fundamental to version control systems, code review workflows, and understanding file modifications. The extension includes related tools from the diff ecosystem including three-way comparison, side-by-side merging, word-by-word comparison, patch application, and change statistics.

Content Coverage:
The extension includes essential diff ecosystem elements:
• Basic diff commands: Line-by-line file comparisons with various output formats.
• diff3: Three-way file comparison for merging changes.
• sdiff: Side-by-side interactive merge utility.
• wdiff: Word-by-word comparison for documents and prose.
• patch: Apply and manage diff patches.
• diffstat: Generate change statistics from diff output.
• Output Formats: Unified (-u), Context (-c), Side-by-side (-y), ed script (-e), RCS formats.
• Directory Comparison: Recursive diff, exclude patterns, treat absent files as empty.
• Whitespace Handling: Ignore case, whitespace, blank lines options.
• Related Utilities: cmp (byte comparison), comm (sorted file comparison), colordiff.

Target Audience:
• System Administrators tracking configuration changes and applying patches.
• Software Developers reviewing code changes and generating patches.
• Version Control Users working with Git, SVN, and Mercurial.
• Release Engineers managing software patches and updates.
• Documentation Specialists comparing document versions.
• DevOps Engineers analyzing system configuration changes.

Use Cases & Practical Applications:
• Code Review: Generate unified diffs for team review, understand changes between versions.
• Patch Creation: Create and apply patches for software distribution and updates.
• Version Control Integration: Understand git diff outputs, resolve merge conflicts with diff3.
• Configuration Management: Track changes to system configuration files across servers.
• Document Comparison: Compare document versions word-by-word with wdiff.
• Release Engineering: Generate change statistics for release notes with diffstat.
• Merge Conflict Resolution: Use three-way comparison to understand and resolve conflicts.
• Directory Synchronization: Compare entire directory trees to identify differences.

Extension Features:
• 118 Comprehensive Entries: Covering all diff tools, options, and practical patterns.
• Instant Search: Real-time filtering by command, option, or description.
• Click-to-Copy: One-click command copying for immediate terminal use.
• Compact Interface: Space-efficient sidebar optimized for quick reference during terminal work.

Security-First Design:
• Zero permissions required.
• No data collection or tracking (explicitly declared in manifest).
• Entirely offline operation.
• Secure DOM manipulation using createElement and textContent only.
• No third-party dependencies or network requests.
• All data stored locally in embedded JavaScript file.
• Local Processing Only: All operations within sidebar with no external calls.
• No risky features: innerHTML, eval, or dynamic code generation avoided.
• Manifest v2 Compliant: Adheres to Mozilla's security standards and privacy requirements.

Technical Specifications:
• Compatibility: Firefox 140+ (64-bit desktop).
• Runtime Execution RAM Footprint: 17 KB (sidebar.js + sidebar.html + manifest.json).
• Total Extension Download/Install Size: 40 KB (including README.md documentation).
• Performance: Instant search response with efficient filtering algorithms.
• Testing: Verified on Firefox 148.0 (February 2026).

File Diff Tools provides immediate access to the complete diff ecosystem, supporting professionals who rely on understanding and managing file differences while maintaining strict security and privacy standards. The extension continues the Unix tradition of powerful, focused tools by delivering diff utility reference information efficiently within the browser environment.