What are some alternatives?
When comparing flpbk.io and Instagfy, you can also consider the following products
GifBook - Make animated GIFs into paper flip books
Tall Tweets for Google Slides - Tweet your Google Slides as animated GIF images
Print A Gif - Turn any gif into a printable flip book
Plotaverse - Photo animation made easy, animate like the pros
simplebooklet - Code free web brochures. Publish, post, pin, tweet, embed, email, print and share everywhere.
GIPHY GIF maker - Create animated GIFs from videos (by Giphy)