SaaStr's 90/10 rule for AI tools: Buy most, build only what's missing

The Gist

• SaaStr advocates buying 90% of tools off-the-shelf and building only 10% where no solution exists
• New 2026 exception: replace tools with zero AI functionality, even if they're paid products
• Built an AI VP of Marketing because no existing solution met their needs

• The 90/10 rule for AI tools: Buy 90% of what you need off the shelf and build only the 10% where no solution exists.
• In 2026, tools without AI functionality will be replaced, as AI features become table stakes.
• Building internal tools first before replacing external-facing paid tools reduces risk and builds expertise.
• Maintenance of vibe-coded apps is a significant and often overlooked cost.
• Every company has 10-20 specific workflows too niche for vendors but too small for engineering teams to prioritize.
• The gap between market offerings and specific needs is where the value of building custom tools lies.

• Adopt the 90/10 rule: Buy 90% of tools off the shelf and build only the 10% where no solution exists.
• Evaluate tools for AI functionality and replace those lacking AI features by 2026.
• Build internal tools first to gain expertise before replacing external-facing paid tools.
• Focus on maintaining vibe-coded apps efficiently to avoid unnecessary time and resource drain.

• 25+ AI agents (SaaStr operates with 25+ AI agents alongside a small human team.)
• 5,000+ pieces of content (SaaStr has over 5,000 pieces of content, totaling 20 million words.)
• $10,000+ per year (SaaStr was paying over $10,000 annually for a niche sponsor portal tool before replacing it.)
• 10-20 workflows (Every company has 10-20 specific workflows too niche for vendors to address.)