GIF to FLIF converter
For permanent links you can use: https://ezgif.com/gif-to-flif?url=https://example.com/image.gif
Output FLIF image:
Online GIF to FLIF (Free Lossless Image Format) converter
Keep in mind, this is an experimental tool. FLIF is a new and constanlty improving format, so there aren't many tools with FLIF support.