[minus7]

FLIF has been superseded[1] by JPEG XL, which, in my very limited testing, performed better (speed and compression-wise; libjxl) than FLIF.

Interesting though that FLIF 0.4 was released 3 days ago. I haven't checked out that new release (and won't), but the previous one wasn't great code and was a pain to use (ended up using its CLI instead of the lib). We ended up going back to PNG because of interoperability and speed. I haven't looked at libjxl's API yet.

Edit: 8605KB in 11.5s with libjxl, so it's not actually better than FLIF 0.4 (7368KB in 23.9s)

[1]: https://flif.info/#update

[nightcracker]

Yes, I am aware it has been 'superseded' but in my experience for lossless compression it's still usually better.