I run https://quailhq.com -- point-of-sale software for antique stores.
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Data: Postgres
APIs: Java + Dropwizard
Frontend: Typescript, transitioning from Angular (1.x) to React
Hosting is on a cluster of cheap Linodes, and transactional email is handled by Postmark. Shout out to both of those services, which have been rock-solid compared to others I've tried. I absolutely think the choice of tech has helped Quail succeed -- it's boring software built with boring technology, which leaves me free to focus on the more interesting parts of the business.