Thank you for the pointer!

I use ect on a monthly basis, at least. Especially for png files. It's pretty great!

Yeah, for how well it does with PNGs it really doesn't get nearly as much attention as the other tools for the same do.

I had no heard of ECT, but I'm not impressed. I've just benchmarked it against two others PNG optimizers, and here are the file sizes for default and max levels:

    1985457 oxipng-o6.png
    2030036 oxipng-o2.png
    2125459 ect-o9.png
    2144598 ect-o3.png
    2169351 optipng-o7.png
    2215086 optipng-o2.png
    2218326 original.png

    oxipng 9.1.5
    OptiPNG version 7.9.1
    Efficient Compression Tool Version 0.9.5

BTW, I could not compile ECT on my Linux system, because its CMake config was too old. I used the Windows release through Wine, but it shouldn't change the results above.

I tried to apply ECT to a few .gz files, but it complained it was not compatible, and I did not dig further.

[edited for a typo s/I/it/]

Good to know that oxipng has surpassed ECT; there is a reason why i put "(still?)" in my original comment. How quick is it? (The main selling point of ECT was that it was way faster than OptiPNG etc. while results being smaller.)