Diff Checker

Online diff checker for text & code with AI summaries. Quickly check diff, text compare and find the difference between versions

Compare two versions of text, code, or files directly in your browser — no uploads to third-party servers, no accounts required. Diff Checker highlights additions, deletions, and modifications between two inputs so you can quickly see what changed. Everything runs locally on your device — your data never leaves your machine. 🔍 What you can compare — Plain text and code in 20+ programming languages with syntax highlighting — JSON structures with automatic format detection — Office documents (DOCX, XLSX) — converted to text right in the browser — Source code of any two open browser tabs, loaded with one click — Uploaded files in various encodings 🤖 AI-powered change summaries (optional) Connect your own OpenAI API key to get concise explanations of what changed between versions. Choose between full-text or diff-only analysis. This feature is entirely optional — the extension works fully offline without it. ⚙️ Comparison settings — Side-by-side or unified (inline) view — Ignore whitespace, case sensitivity toggles — One-click code formatting for popular languages and data formats — Normalize content: sort object keys, clean up whitespace, reorder style properties — Stats at a glance: lines added, removed, modified — Copy results or selected lines with one click — Local comparison history to reopen recent sessions 🔒 Privacy All comparisons happen locally in your browser. The extension does not log, store, or transmit your data. No external servers, no tracking, no analytics. When AI summaries are enabled, data goes to OpenAI only at your request — this is fully under your control. 💡 Typical use cases — Reviewing code changes before a commit — Comparing markup and styles between staging and production — Tracking edits in documents or reports — Validating JSON payloads during API testing — Comparing configuration files across environments — Checking assignment revisions ❓ FAQ How does it work? Paste two blocks of text, upload files, or pick two open tabs — then click Compare. Differences are highlighted with color coding. Does it need an internet connection? No. Everything works offline. Only AI summaries require a connection and your OpenAI API key. Is my data sent anywhere? No. All processing is local. AI features send data to OpenAI only when you explicitly enable them. Does it support large files? Yes. The engine is optimized for large inputs without freezing your browser. Can I export results? You can copy results to clipboard. A full export feature is planned for a future update. 📋 Recent updates v1.1.6 — One-click code formatting for 20+ languages. Content normalization. Split/unified view toggle. v1.1.5 — Office file support (DOCX, XLSX). Better error handling and UX polish. v1.1.4 — Diff stats in headers. Copy button for code and selected lines. Cleaner UI. v1.1.3 — AI-powered diff summaries. Local comparison history. Performance improvements. v1.1.2 — Better syntax highlighting and language detection. v1.1.1 — Initial release with side-by-side diff, line numbers, theme support.