Imo you will have to get outsourced on-call if your downtime tolerance is very very low. Otherwise I'd suggest religiously documenting your outage root causes

Imo you will have to get outsourced on-call if your downtime tolerance is very very low. Otherwise I'd suggest religiously documenting your outage root causes and contemplating hard what could've avoided that outcome. Then lastly for monitoring on the cheap: Sentry.io - alerts. Opsgenie - on-call management. Heroku+new relic - heartbeat & performance. Tldr; Keep your stack small and nimble and try to learn from past outages