What are some alternatives?
When comparing Comixology Unlimited and Piperka, you can also consider the following products
GlobalComix - Professional Comics Publishing
Tapas - Tapas – Comic, Novel and Stories is free to use digital comic application by Tapas Media that puts tens of thousands of comics and web novel on your mobile device.
LINE Webtoon - LINE Webtoon is a digital comics platform with various comics for free on web and mobile.
HalftonePro - Create custom vector halftones quickly and easily
MangaDojo - MangaDojo is a community for manga artists and readers from all around the globe!
Marvel (Comics) API - Create awesome stuff with the world's greatest comic API