How this image compressor works
Drop in an image, pick JPEG or WebP, and drag the quality slider — the tool re-encodes the image on a canvas and updates the compressed size, the percent saved and the live preview a moment after you stop moving the slider. When the balance of size and quality looks right, download the result. Because everything runs locally, a 20 MB photo compresses just as quickly as a small one; there is no upload and no queue.
The biggest savings come from format changes, not just the slider. A screenshot or photo saved as PNG is stored losslessly and is often enormous; re-encoding it as JPEG or WebP at quality 80 routinely cuts it by 80–95%. Pure PNG-to-PNG optimization is the one thing a browser canvas cannot do — see the FAQ below for the honest details.
Choosing a quality level
Lossy encoders spend bits where your eyes notice them, so the quality-to-size curve is steep at both ends. Between 80 and 85 most photos are visually indistinguishable from the original at a fraction of the size — that is why 80 is the default here. Below about 60, blockiness and smeared detail creep in, especially around text and sharp edges. Above 90, file size climbs rapidly for improvements you will struggle to see. Transparent images encoded to JPEG get a white background, since JPEG has no alpha channel — use WebP to keep transparency.
Compress smarter: resize first
Quality settings only go so far if the image has far more pixels than its destination needs. A 4000px-wide photo shown in a 800px column wastes bandwidth no matter how it is compressed. Run oversized images through the Image Resizer first, then compress the result here — the combination often beats either step alone by an order of magnitude. Shipping a website? Minify your stylesheets too with the CSS Minifier.