Question 1

Next.js or a separate React frontend + Python backend?

Accepted Answer

Default to Next.js App Router with server actions for tighter coupling and faster shipping. I split into separate frontend + FastAPI when you have a non-web client (mobile, native, embedded device) that needs the same API, or when the backend's compute profile (heavy Python ML, long-running jobs) doesn't fit a serverless function. Decided in week one.

Question 2

How do you handle auth — Supabase, Clerk, NextAuth, custom?

Accepted Answer

Supabase Auth or Clerk for most SaaS builds — both are battle-tested and ship faster than rolling auth from scratch. Custom JWT + bcrypt + DB sessions only when there's a specific reason (HIPAA-compliant audit trail, integration with an existing identity provider, etc). 2FA via TOTP is included on every auth I ship.

Question 3

What scale can a solo-built SaaS actually handle?

Accepted Answer

Vercel + Supabase + a 12 M-row Postgres dedupe index serves 8 production tenants today at 0.08 s p50 query latency. Real numbers from the B2B lead-gen SaaS in the case studies. Past 100 K daily active users you start needing dedicated infra and a team — but most founders never get there alone, and by then revenue funds the engineers.

Question 4

Do you handle billing — Stripe, paddles, etc.?

Accepted Answer

Yes. Stripe Subscriptions + webhooks is the default. I wire metered billing, plan upgrades, prorations, dunning emails, and a customer portal. Paddle and Lemon Squeezy when you need merchant-of-record for tax reasons.

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