Should I build or buy?

Buy (use existing solutions) when:

• Speed to market matters most
• The feature is standard (authentication, payments, email)
• You're still validating your core idea
• Someone else has already solved the problem well
• The cost is reasonable relative to your time

Build when:

• The feature is core to your differentiation
• Existing solutions don't quite fit your use case
• Long-term costs of buying are prohibitive
• You need control over the implementation
• The learning has strategic value

Examples:

• Authentication: Buy (Supabase Auth, Clerk, Auth0). Don't build your own.
• Payment processing: Buy (Stripe, Lemon Squeezy). Seriously, don't build this.
• Email delivery: Buy (Resend, SendGrid). Deliverability is a nightmare to handle yourself.
• Your core product feature: Build. This is where AI tools shine.