To help Etsy sellers support charitable causes with purchases from their shops, I developed a platform that integrated with Etsy's API. This platform made it easy for sellers to support one or more causes and promote those causes as part of marketing campaigns. With the promotion tools, sellers could choose suggested messaging or provide their own, and the messaging would be pushed to selected listings in their shops, even placing a banner on the listings' primary images if desired.
I made heavy use of queued jobs with Amazon SQS to support horizontal scaling across worker nodes. I used Elastic Beanstalk for easy load balancing and deployment of the main application, as well as ElastiCache with Redis for the caching layer. MySQL on RDS served as the database backend. The frontend was a single-page app in React.