The Free Lossless Image Format (FLIF) is a new lossless image format. It works well on any kind of image (e.g. photographic or clipart), and it is “Responsive By Design”.
FLIF is fully functional (see e.g. http://cloudinary.com/blog/flif_the_new_lossless_image_format_that_outperforms_png_webp_and_bpg for an independent evaluation), but it is currently still experimental. The current work-in-progress implementation is released under the GNU GPLv3+. We are working to finalize the format, and we will release a decoder library under a more permissive license (most likely GNU LGPLv3+).
Once the format is finalized, there is still a lot of work to be done to let FLIF evolve from an experimental research prototype to a mature, widely supported standard image format. With your help we can get there!