I found it surprising that PunyPNG beat OptiPNG on every single benchmark, given that the first/only png I uploaded was reduced into <i>exactly</i> the same file with the same number of bytes by PunyPNG and OptiPNG.<p>In most of the benchmarks the performance is very similar. It seems that only certain types of image (images that would be better as jpegs anyway?) are dealt with much better by PunyPNG, which dominates the overall comparison.<p>I doubt I'll ever use punypng. For something like this I don’t want a web service. I'll stick with the free software OptiPNG, which is packaged by my favorite OS distributions.