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A modern image format by Google offering both lossy and lossless compression with smaller file sizes than JPEG/PNG.
Google released WebP in 2010 as a modern image format engineered to provide superior compression for both lossy and lossless images compared to JPEG and PNG. WebP lossy compression uses predictive coding based on VP8 video codec technology to achieve 25-35% smaller file sizes than equivalent-quality JPEG, while WebP lossless compression produces files approximately 26% smaller than PNG. The format also supports transparency (alpha channel) in both lossy and lossless modes — a combination that neither JPEG (no transparency) nor PNG (no lossy compression) offers. WebP has achieved universal browser support, with Chrome, Firefox, Safari, and Edge all rendering WebP natively, and major platforms including WordPress, Shopify, and Cloudflare now serve WebP images by default for compatible browsers.
Image CDNs like Cloudinary, imgix, and Fastly auto-convert uploads to WebP for bandwidth savings. The format supports animation as a replacement for GIF with dramatically better compression, and includes ICC profile embedding and EXIF metadata. Google's cwebp and dwebp tools handle encoding and decoding, while ImageMagick, Sharp (Node.js), and Pillow (Python) provide programmatic WebP support. The container format is based on RIFF (the same structure as WAV audio), and the specification is openly documented.
Modern web development best practices recommend WebP as the primary delivery format with JPEG/PNG fallbacks for legacy browsers. Next.js, Nuxt, and other frameworks include built-in image optimization that automatically generates WebP variants. As websites increasingly prioritize Core Web Vitals and loading performance, WebP's compression advantages make it a standard part of performance-conscious image pipelines.
WebP comparison is essential when migrating image assets from JPEG and PNG to verify that the format conversion preserves visual quality at the target compression level. Comparing WebP files catches quality degradation from overly aggressive lossy settings, transparency artifacts that appear after converting from PNG, color profile discrepancies between the original and converted image, and animation frame differences when replacing GIF with animated WebP.
Development teams need visual diff to validate that image optimization pipelines produce acceptable output across their asset library.
UtraDiff compares WebP images using four visual diff modes: pixel overlay highlights changed pixels in a contrasting color, heatmap shows change intensity with a gradient, onion skin crossfades between versions with an adjustable opacity slider, and side-by-side renders both images at matched scale. Both lossy and lossless WebP variants are supported, with a tolerance threshold available for lossy files to suppress compression artifact noise.
Image dimensions and format metadata are reported alongside.
Supported extensions: .webp