PaaS vs IaaS vs SaaS: What Each Means and Who Should Pick What in 2026

Author: Angelo Saraceno Most engineers learn “PaaS vs IaaS vs SaaS” from a single slide in a 2014 textbook. The slide that was right in 2014 is incomplete in 2026. The industry built the three-tier model (IaaS, PaaS, SaaS) to explain cloud computing to people who had only ever bought servers, and it worked. Two new tiers have arrived since then: FaaS (Functions-as-a-Service) and what I call agentic-PaaS, where the platform exposes itself to LLM agents as a first-class consumer. If you are choosi