Convert images between PNG, JPEG, WEBP, and AVIF formats entirely in your browser. No uploads, fully offline, with batch processing and ZIP download support.
- ✅ Offline Conversion — All processing happens in your browser using the Canvas API
- 🎨 Multiple Formats — Convert between PNG, JPEG, WEBP, and AVIF
- 📊 Quality Control — Adjustable quality slider for lossy formats (JPEG, WEBP)
- 📦 Batch Processing — Convert up to 10 images at once
- 🗜️ ZIP Download — Download all converted images as a single ZIP file
- 📏 Size Comparison — See before/after file sizes with percentage change
- 🎯 Drag & Drop — Easy file selection via drag-and-drop or file picker
- 🌓 Dark Mode — Toggle between light and dark themes
- 🔒 Privacy First — No data ever leaves your browser
- PNG
- JPEG
- WEBP
- GIF (first frame only)
- BMP
- AVIF (Chrome 94+)
- PNG (lossless)
- JPEG (lossy, quality adjustable)
- WEBP (lossy, quality adjustable)
- AVIF (lossy, Chrome 94+)
- Select Output Format — Choose your desired output format from the dropdown
- Adjust Quality — For JPEG/WEBP, set the quality slider (1-100%)
- Add Images — Drag and drop images or click the drop zone to browse
- Wait for Conversion — Images are converted automatically
- Download:
- Click "Download" on individual files
- Click "Download All as ZIP" to get all files in one archive
- Canvas API — Uses
HTMLCanvasElement.toBlob()for format conversion - No External Libraries — Pure vanilla JavaScript
- ZIP Generation — Minimal ZIP implementation without compression
- Quality Preservation — Maintains original image dimensions and color depth
- Memory Efficient — Processes files one at a time
This extension requires only the storage permission to save your theme preference. No host permissions are needed.
- Chrome 92+ (for full WEBP support)
- Chrome 94+ (for AVIF support)
- Firefox (with WEBP support)
- Edge 92+
Coming soon
- Download or clone this repository
- Open Chrome and navigate to
chrome://extensions - Enable "Developer mode" (top right toggle)
- Click "Load unpacked"
- Select the extension folder
If this extension helped you, consider supporting the developer:
- ☕ Buy Me a Coffee
- 💖 GitHub Sponsors
- 🍵 Ko-fi
- 💸 PayPal
This extension:
- ✅ Works completely offline
- ✅ Does not collect any user data
- ✅ Does not make any external network requests
- ✅ Does not upload any files
- ✅ Only stores theme preference locally
MIT License - feel free to use, modify, and distribute.
- Image format conversion (PNG, JPEG, WEBP, AVIF)
- Quality control for lossy formats
- Batch processing (up to 10 files)
- ZIP download for multiple files
- File size comparison
- Dark/light mode support
- Drag and drop support