Which formats can I convert between?

PNG, JPG, WebP and (in supporting browsers) AVIF, in any direction. The quality dial applies to lossy formats like JPG, WebP and AVIF.

Is my image uploaded anywhere?

No. The conversion runs entirely in your browser using the canvas engine — you can watch the network panel and see nothing leaves your device.

Re-encoding a heavily compressed image into a different format can grow it. Try WebP or AVIF at quality 0.8–0.9 for the best size/quality balance.

Yes — free, no account, no daily limits, and it works offline once the app is cached.

BMP is uncompressed and enormous. JPG typically takes it down by an order of magnitude, which is usually the whole point of the conversion.