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UseCOS Image Converter transforms WebP, PNG, and JPG images directly inside your browser utilizing the HTML5 Canvas 2D Rendering Context and OffscreenCanvas API. Your photos and sensitive graphics are never uploaded to any remote server or stored in the cloud.
Convert WebP to PNG, PNG to JPG, JPG to WebP, and more. 100% private, unlimited conversions in your browser with zero server uploads and zero file size limits.
1-Click Conversion Presets
Supports WebP, PNG, JPG, JPEG, BMP • Unlimited files • 100% private in browser memory
Traditional converter sites require uploading your personal photos to their servers, posing privacy risks and download wait times. UseCOS converts multiple images simultaneously on your device CPU/GPU in milliseconds with zero bandwidth waste.
Technical performance benchmarks (2026) across modern raster formats for Core Web Vitals (LCP) and visual fidelity.
| Format & Container | Compression Engine | Alpha Transparency | Size Savings vs Master | Recommended Use & Caveats |
|---|---|---|---|---|
| WebP (.webp) | Lossy or Lossless (VP8/VP8L) | 8-Bit Alpha Supported | 25% – 35% smaller than JPG | Best all-round web format. Dramatically improves Core Web Vitals (LCP). Compatible with 97%+ of modern browsers. |
| PNG (.png) | Lossless (Deflate / LZ77) | Full 8-Bit Alpha | Master baseline (0%) | Essential for UI icons, transparent brand logos, and sharp vector-raster exports. Avoid for large photographic hero banners. |
| JPEG / JPG (.jpg) | Lossy (Discrete Cosine DCT) | No Alpha (Flattens to White) | 50% – 70% smaller than PNG | Universal standard for camera photos, real estate listings, and legacy email clients. Discards transparency entirely. |
| AVIF (.avif) | Lossy / Lossless (AV1 Codec) | 10/12-Bit HDR Alpha | 40% – 50% smaller than JPG | Highest compression efficiency. Requires fallback for legacy systems; slower CPU encoding time during batch conversion. |
Converting to JPEG discards transparency (any alpha channel is flattened onto a white background), and no format here preserves animation -- an animated GIF or WebP converts to a single still frame. ICC color profiles and EXIF metadata (camera model, GPS location, orientation tag) are not carried over, since the browser Canvas API strips them during redraw.
Calculations and media conversions execute locally inside client memory. No files, personal figures, or data records ever transit through external cloud servers.
Conforms to W3C HTML5 Canvas & Google WebP Container Specification.
Authored by UseCOS Research & Engineering.