About LeanImg

LeanImg provides free online image tools that work entirely in your browser. No files are ever uploaded to any server — all processing happens on your device using WebAssembly-powered codecs.

How It Works

When you compress an image with LeanImg, the processing happens using industry-standard codecs compiled to WebAssembly:

• MozJPEG — Mozilla's optimized JPEG encoder, producing 20–30% smaller files than standard JPEG compression
• OxiPNG — A Rust-based PNG optimizer for lossless size reduction
• WebP — Google's modern image format for excellent compression at high quality
• AVIF — The latest image format based on AV1 video compression

Privacy

Your images never leave your device. There are no uploads, no temporary storage, no server-side processing. This isn't just a claim — you can verify it yourself by checking your browser's network tab during compression. You'll see zero network requests related to your images.

Open Source Codecs

The compression codecs used by LeanImg are open-source projects maintained by Mozilla, Google, and the Rust community. We use the jSquash library to bring these codecs to your browser via WebAssembly.