After several years on and off development I have launched
VendBits, a marketplace for digital products.
https://vendbits.com
The general idea is to allow users to sell any type of digital product: images (photos, digital art, stock photos), audio (audio books, sound effects, music), videos (movies, vlogs, stock video), software (games, WordPress themes & plugins, scripts), domain names, writings (stories, articles) and accept PayPal, Stripe (CC billing, soon to be integrated), Bitcoin and Bitcoin Cash.
I have also released an API in alpha stage with endpoints for retrieving, adding, editing and deleting the items for sale.
https://vendbits.com/api
I plan on building out more endpoints to match the functions of the web app such as user registration, login, password reset, uploading avatars, search results, tag results, category results, edit profile, edit settings, etc..
I used the Laravel PHP framework for the web app and API which I have become familiar with over the past few years.
So far, I have only built the endpoints for retrieving, adding, editing and deleting the items for sale.
Please go ahead and post your feedback here as I would love to get some of your input. Cheers!