For our SAAS we're running:

- DB Engine: MariaDB on RDS (multiple instances) + Redis for specific use cases. - API layer: Symfony (PHP) - Frontend : React - Caching: Redis - Ops: Rancher Orchestration on EC2, and a bunch of AWS features like S3, ALB, ...

We had some hiccups here and there, but I'd say we are happy with the stability of it.