Our platform is service-oriented with around 20 services (all in Ruby). Most services are on Rails and use either ActiveRecord or Sequel to talk to the database (Postgres). Services talk to each other either over HTTP or SQS. We build constantly using CircleCI and deploy on-demand to Docker running on AWS in production. There are bits of React here and there.
We’ve built a platform which can do everything needed to sell retail electricity - integrate with the electricity market, invoice customers, manage our relationship with those customers, and so on. We’re now building on that platform and exploring what we can do beyond just selling electrons - offering different brands on our platform, letting people buy power in different ways, and helping people to understand their usage so they can make better environmental choices, among much else.