Compress PNG

No. PNG here is optimised with OxiPNG, which is lossless - it rewrites the file more efficiently without touching a single pixel or the transparency. The image is byte-for-byte identical to the eye; only the file is smaller.

Lossless PNG optimisation typically saves anywhere from a few percent to 30% or more, depending on how the file was originally saved - screenshots and exported graphics usually shrink the most. Raising the Effort level searches harder for savings at the cost of speed.

Interlace (Adam7) changes the byte order so the PNG can display progressively as it loads, rather than top to bottom. It does not change how the image looks and often makes the file slightly larger, so leave it off unless you specifically want progressive loading.

No. Decoding, resizing, compression and ZIP packaging all run inside your browser using WebAssembly codecs. Your images never leave your device and nothing is sent to a server, so it works offline and is safe for private photos.

Yes. Drop multiple files, a folder or a ZIP. Each image keeps its own settings (a new one inherits whatever you last used); to apply the current settings to several at once, select them and use "Apply current settings". Download them individually or as one ZIP.