How Batch Image Conversion Works in Your Browser
Modern browsers support high-performance off-main-thread image processing using Web Workers and OffscreenCanvas. By decoding and re-encoding raster image data locally, you can convert dozens of pictures instantly without uploading sensitive files to any external cloud server.
Supported Formats & Best Use Cases
- WebP: Next-generation image format offering superior lossy and lossless compression. Reduces file size by 25–35% compared to JPEG while preserving visual fidelity. Ideal for web performance and SEO Core Web Vitals.
- JPEG / JPG: Universal lossy compression standard best suited for photographic content and complex imagery where high color depth is required.
- PNG: Lossless compression supporting full alpha transparency. Perfect for logos, interface mockups, icons, and illustrations with sharp geometric boundaries.
Frequently Asked Questions
- Are my images uploaded to any server?
- No. All conversion and ZIP archiving operations execute 100% inside your local browser memory using HTML5 Canvas, Web Workers, and JSZip. Your images never leave your device.
- How many images can I convert at once?
- You can convert batches of up to 20 images or 50MB in total aggregate size per batch. This guardrail prevents mobile tabs from running out of memory.
- How do I download all converted images together?
- Once your images finish processing, click the "Download All (.zip)" button. The tool will bundle all transcoded images into a single compressed ZIP file for fast extraction.