Open Source vs SaaS: Where to Draw the Line

As engineers, we love to build. We love to self-host. “Why pay Datadog $5,000/month when I can run Prometheus for free?”

Because Prometheus isn’t free. You pay for it with your time.

The Framework

Here is the rule we use at ClusterCost to decide between OSS and SaaS:

1. Is it Core Business? -> BUILD (OSS) If it is your unique value proposition, you must own it. For us, the Cost Agent is core. We build it. We open-source it.

2. Is it a Commodity? -> BUY (SaaS) Email sending (SES). CRM (Attio). Payments (Stripe). Building these yourself is madness. It distracts you from your product.

3. The Grey Area: Observability This is the hardest one. Self-hosting ELK/Prometheus is cheaper in dollars but expensive in maintenance. Rule: If you have a dedicated Platform Team, self-host. If you are a startup of 5 people, buy the SaaS. Your time is worth more than the bill.