It's quite diverse given few M&A along the way. To put it simply, a number of VMs scattered across different providers, hosting services. Services range from load balancers (haproxy), frontend/backend endpoint servers (nginx, varnish), code (PHP, RoR, etc),CDN (nginx), database (MariaDB, PostgreSQL), ELK... Icinga for monitoring everything, Grafana to see trends and big picture. Tableau, Dataiku for BA.