Compress images

JPG and WebP are compressed keeping their format. PNG is converted to WebP, because PNG is lossless and compressing it without changing format does not reduce the size at all: the browser ignores the quality setting and hands back a practically identical file. As WebP the same image can weigh 5% of what it did, with transparency intact. If you need the PNG for compatibility, there is a switch in advanced options. BMP is also converted to PNG, because browsers cannot write BMP. AVIF and GIF are not accepted: the first already uses better compression than anything we could produce, and the second would lose its animation. If what you want is to change format on purpose, rather than just shrink the file, that is what Convert images does.

There is no hard limit. We recommend up to 50 MB per file to avoid hanging older devices. There is a second limit that depends on dimensions rather than weight: an image with a huge number of pixels can exceed what the browser handles even when the file is small. If that happens we tell you on that image, and the rest keep going. To change dimensions on purpose, rather than just the weight, there is Resize images.

Yes. WebP supports transparency just like PNG, including partial transparency: a soft edge or a gradient shadow comes back with its values intact. We checked this with fully transparent and gradient-alpha images before enabling the conversion.

No. All processing happens in your own browser using JavaScript. You can disconnect from the internet after loading the page and the tool keeps working.

Yes. Drag as many as you want. They process 3 at a time in parallel, to avoid overloading your device, and become available for individual or ZIP download.