How it works
From original to optimized — without leaving your browser
No upload, no waiting on a server. Here's exactly what happens when you optimize an image with Lean Image.
Four simple steps
Add your images
Drag and drop files anywhere on the page, paste from your clipboard, or click to browse. Add one image or a whole batch.
Choose your settings
Pick an output format (WebP, AVIF, PNG, JPEG, or GIF) and set quality — or set a target file size and let Lean Image hit it for you. Resize and crop if you need to.
Optimize in your browser
Lean Image processes everything locally using Web Workers, so it’s fast and your images never leave your device.
Download
Compare before and after, then download images one by one or all together as a ZIP.
What you can do
Convert between formats
Turn PNGs into WebP, iPhone HEICs into JPEG, and more. Lean Image reads JPEG, PNG, WebP, GIF, AVIF, HEIC, JPEG XL, BMP, TIFF, and SVG, and writes WebP, AVIF, PNG, JPEG, and GIF.
Compress to a target size
Set a maximum file size and Lean Image searches for the best quality that fits, shrinking dimensions only if it has to.
Resize & crop
Use dimension presets or custom sizes with contain, cover, or stretch fit modes — and crop to any aspect ratio with a live editor.
Batch everything
Process many images at once with shared settings, then override any single image when you need something different.
Compare instantly
A draggable before/after slider and a clear savings badge show exactly what you gained.
Download your way
Grab files individually or download the whole batch as a single ZIP archive.
Under the hood
Lean Image leans on capabilities built into every modern browser. When you add an image, it's decoded and drawn onto an OffscreenCanvas inside a Web Worker — a background thread — so the interface stays responsive while your images are processed. A small pool of workers runs several images in parallel, scaled to your device's CPU.
To hit a target file size, Lean Image uses a binary search: it encodes the image a handful of times, honing in on the highest quality that stays under your limit. For AVIF, a WebAssembly encoder runs the compression locally, right in the worker.
The result is a tool that's both fast and completely private — because the entire pipeline, from decode to download, happens on your machine.
Why in-browser is better
Private by default
Your files are processed where they already are. Nothing is uploaded, so nothing can be intercepted, logged, or kept.
No upload, no wait
Skip the round-trip. There's no slow upload of large images and no download of the result from a remote server — it's all instant and local.