A practical guide
Re-encode PNG pixels without pretending every file will shrink.
PNG is a lossless format commonly used for screenshots, interface graphics, diagrams, logos, and images that need transparent pixels. PixelShrink asks the browser to create a fresh PNG from the decoded image. The pixels and alpha can remain intact, but the browser controls its encoder and an already optimized source may not become smaller.
Unlike JPG or lossy WebP, the PNG quality slider does not provide a meaningful size-versus-detail tradeoff here, so it is disabled. Complex photographs often produce large PNG files because lossless encoding must preserve every pixel exactly. If lossless output is not required, compare a WebP or JPG conversion instead; choose JPG only when transparency is unnecessary.