Evolution of the 90/10 Rule

SaaStr 842: The 90/10 Rule for AI Agents: What to Build vs Buy with SaaStr's CEO and CAIO

SaaStr's Chief AI Officer, Amelia Lerutte, and SaaStr CEO & Founder Jason Lemkin break down SaaStr's evolving 90/10 rule for AI agents and apps: buy 90% off the shelf, build the 10% you can't find.

In this episode, they walk through two recently built tools: an internal AI VP of Marketing and an external-facing customer portal, and share the real trade-offs of deploying vibe coding apps into production.

Topics covered: Why we replaced a paid SaaS tool with a vibe-coded app (and what pushed us over the edge) How Claude Cowork changed the game for building more complex apps The role of writing a spec before vibe coding Tackling single sign-on as a non-engineer How we used Cowork to process 150+ customer contracts in hours instead of days Lovable's data on what people are actually vibe coding Maintenance costs and the hidden time suck of custom apps Why zero AI in your product should scare you The "jaw drop" test for SaaS products in 2026 -------------------------------------- Tools & resources mentioned: Replit, Claude Cowork, Clerk, Lovable, Zapier, Salesforce, Monaco 🔗 See all the AI agents and tools we use: saastr.ai/agents 🔗 SaaStr Annual 2026 (May 12-14): saastrannual.com 🎙️ 20VCwith Harry & Jason & Rory: Drops every Thursday #SaaStr #AI #VibeCoding #B2BSaaS #AIAgents #BuildvsBuy --------------------------------------

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