PNG is the web's lossless image format. It compresses without ever degrading the picture and has a real alpha channel, which is why screenshots, logos, line art and anything with sharp edges or text belong in it. The trade is size: on a photograph, PNG is enormous compared to JPG.

Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop a PNG file above and choose afterwards.