I'm organizing a Story Origins Sci-Fi group promo. Story Origins operates the same way as Prolific Works, BookFunnel, and MyBookCave Magnet promos do: you offer a novel, novella, or short story in return for an email address. The advantage over BookFunnel and Prolific Works is that for the time being it is free. It's also extremely easy to use. Authors in the promo share the promo with their social media audiences and email lists.
Anyway, if you want to sign up for an account, here is the link to Story Origins:
https://storyoriginapp.com/If you have a Story Origins account, here is the promo link:
https://storyoriginapp.com/bundles/a634280e-37a4-11e9-bb59-c34e6600667d/infoCheers!