worse than tinypng.com

[cos2004]

I guetzli a jpg image(quality:84), compare with tinypng.com, tinypng is smaller... feel so confused...

[kornelski]

File size depends on quality. It's very easy to make a smaller file that has lower quality. In JPEG even a tiny difference in quality can decrease file size a lot.

Guetzli's advantage is having relatively small file for the very high quality it gives. Other tools will either give lower quality or larger file, but you're unlikely to find one that beats it on both.

I've made a presentation explaining that in depth:
https://ldnwebperf.org/sessions/snake-oil-in-image-compression-how-to-ensure-youre-getting-best-quality-and-file-size/