Convert a transparent PNG without adding an unwanted background
PNG is common for screenshots, diagrams, icons and transparent artwork. Its size depends strongly on the content and the existing compression. This converter preselects WebP and provides a lossless option. Alpha transparency can remain in the WebP result, so there is no need to add a white background. Try lossless encoding first for small text or interface screenshots, then compare lossy output if your size requirement allows it.
Lossless WebP does not guarantee a smaller file than the PNG. Repeated patterns, colour variation and the source compressor all affect the outcome. With lossy settings, inspect fine lettering and partly transparent edges, particularly when artwork will sit on a dark background. The checkerboard in the preview indicates transparency; it does not become a background in the downloaded image.
Worked example
A transparent 160 by 100 pixel PNG converted without changing dimensions produces a 160 by 100 WebP. Compare the edges against the preview background before using it elsewhere. If you choose a lossless output, the result can still be larger than the original PNG. Use the actual displayed byte count rather than treating the format name as a size promise.
Local processing and limits
One supported static image is processed at a time. The general input limit is 10 MiB and twelve million pixels; AVIF processing is limited to four million pixels. Unsupported animation, image sequences, HDR and unverified container features are refused. Large images need more memory even when their compressed file is small. A failed operation does not switch to a server-upload fallback.
The browser downloads its own application and codec resources from the same host. Your selected image, result, filename and metadata are not sent to an upload service. Images are not written to localStorage, IndexedDB or a service-worker recovery cache. Reloading the page leaves the image workspace empty. Downloaded files remain under your control; inspect them before sharing.