WebP gave me alpha transparency with lossy images, which came in handy at the time. It was also not bogged down by patents and licensing. Plus like others said, if you support vp8 video, you pretty much already have a webp codec, same with AV1 and avif

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archerx 4 hours ago | parent [-]

Lossy PNGs exist with transparency.

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adzm 3 hours ago | parent [-]

Do you mean lossless? PNGs are not lossy. A large photo with alpha channel in a lossless png could easily be 20x the size of a lossy webp

	▲	Semaphor 2 hours ago \| parent \| next [-]
		PNG of course can be lossy. They aren’t great at it, but depending on the image can be good enough.
	▲	archerx an hour ago \| parent \| prev [-]
		No I meant lossy. This is the library I use; https://pngquant.org/