Diff Viewer

Lightweight offline diff comparison tool for text and code.

Diff Viewer is a developer-focused text comparison tool that runs entirely inside your browser. Paste any two pieces of text — source code, JSON, config files, prose, SQL, logs — and instantly see exactly what changed. No servers. No accounts. No telemetry. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ✦ CORE FEATURES ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ▸ Side-by-Side & Inline diff views Switch between a two-column layout or a unified inline view at any time — even after comparing. ▸ Word-Level Diff Highlighting Toggle granular word-level highlighting inside changed lines so you can spot exactly which words were added, removed, or modified. ▸ Smart LCS Algorithm Uses an optimized Longest Common Subsequence (LCS) engine with integer line hashing for fast, accurate diffs on large files. ▸ JSON Formatter One-click pretty-print for both panels before comparing — perfect for minified API responses. ▸ Live Statistics See added, removed, changed, and unchanged line counts at a glance in the stats bar. ▸ Panel Resizer Drag the center handle to resize the input panels to any split ratio you prefer. ▸ Swap Panels Instantly flip original ↔ modified with one click. ▸ Copy to Clipboard Copy either panel's content independently with visual confirmation feedback. ▸ Session Persistence Your text is remembered across popup open/close cycles within the same browser session. ▸ Keyboard Shortcuts · Ctrl/Cmd + Enter → Compare · Escape → Clear · Tab (in textarea) → Insert real tab character · Arrow keys → Resize panels (keyboard) ▸ RTL Language Support Full right-to-left layout for Arabic, Hebrew, Farsi, and other RTL locales. ▸ Dark & Light Mode Automatically follows your system preference via prefers-color-scheme. ▸ Accessibility First ARIA roles, live regions, keyboard navigation, and focus management throughout. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ✦ PRIVACY — THE SHORT VERSION ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ • Zero network requests — ever. • No analytics, no crash reporting, no ads. • Text you paste is NEVER sent anywhere. • All processing happens locally in your browser. • No permissions to read your tabs, history, browsing data, or any web page content. Learn more in the extension's privacy policy.* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ✦ PERFECT FOR ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Developers comparing code snippets or config files Comparing JSON API responses before & after a change Reviewing contract or document revisions Checking log file differences Comparing SQL queries or database schemas Any situation where you need a quick offline diff ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ✦ TECHNICAL DETAILS ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ • Manifest V3 • Content Security Policy: script-src 'self' only • No external scripts, fonts, or CDN resources • No background service worker • No content scripts injected into web pages • All code is self-contained and auditable * Privacy policy subject to change at any time; any changes will be announced