Vibe Coding Tutorial: Build SaaS That Scales

Most "vibe coding tutorial" content teaches you to build a to-do list. This one assumes you want to ship something people pay for. That changes everything, because the hard part of a SaaS was never the framework or the button that says "Sign up." It's the plumbing underneath — billing, security, email — and that's exactly where vibe coding either saves you weeks or quietly ruins your launch.

Here's how to use an AI agent to build real software, what it's genuinely good at, and where you still have to do the thinking.

What Is Vibe Coding (and What It Actually Solves)

Vibe coding means describing your intent to an AI agent instead of writing every line by hand. You say "add a subscription plan with a monthly and annual price," and the agent writes the Stripe calls, the database rows, and the webhook handling.

It works now because agents have become reliable at deterministic, repeatable tasks — the kind of wiring that follows the same pattern every time. That's the sweet spot.

What it is not: magic. It won't design your architecture, and it won't let you skip understanding how your app works. If you can't tell when the agent's output is wrong, you can't ship it.

The real win isn't "learning to code without learning to code." It's offloading the boring integration work so you spend your attention on the product.

The Stack That Matters More Than the Agent

Vibe coding fails hardest on bad architecture. An agent dropped into a chaotic codebase produces chaotic output — it pattern-matches, and if there are three ways to fetch data, it adds a fourth.

That's why the stack matters more than the agent. Nuxt + Supabase + Stripe + Resend works well together not because each is best-in-class in isolation, but because each has a clear contract an agent can reason about. Supabase gives you auth fast, but row-level security is the part everyone forgets. Stripe's real product is the webhook, not the checkout page. Resend is simple to send with but annoying to send exactly once.

The tool that ties this together for agents is an AGENTS.md file: one documented way to do data access, secrets, and error handling. Give an agent conventions instead of guessing and its output stays consistent past month three. You're trading maximum flexibility for something an agent can hold in its head.

Vibe Coding Your First SaaS: From Brainstorm to Webhook

A workflow that actually produces a shippable app:

Describe the problem, not the solution. "Users need to pay monthly and lose access when they cancel" beats "add a Stripe subscription."
Let the agent interview you. This is the BoiledPlate model — the agent asks about your app name, languages, billing model, and theme before it writes anything.
Watch it provision services. Stripe products and webhooks, a Supabase database with RLS, Google sign-in — provisioned in one session, not clicked together across five dashboards.
Validate the plumbing before writing features. Trigger a test payment. Confirm the webhook fires and the database updates.

What beginners miss: testing webhook delivery and idempotency before launch. A payment that succeeds in Stripe but never reaches your database is a customer who paid and got nothing.

The Plumbing Nobody Talks About (But Eats 80% of the Time)

This is where the difference between a tutorial app and a product lives.

Webhook idempotency. Stripe retries. If your handler runs twice, does the user get charged twice, or granted access twice? An idempotent webhook handles repeated calls without duplicating side effects.

Billing state as source of truth. Never trust a client-side success page. The user's card can succeed while their browser closes. Your checkout success page should not touch your billing state — the webhook is the source of truth.

Refund and consent flows. EU law has real edge cases. A German withdrawal waiver has to be encoded into the pay button itself, not bolted on after. An agent won't know this unless you tell it.

RLS mistakes. Agent-generated row-level security often looks right and still leaks data — a policy that checks the wrong column, or forgets one table entirely. Review every rule.

Email delivery. Transactional email (receipts, password resets) is not marketing email. Resend handles the sending; you still have to think about bounces and retries.

How to Write Prompts So Agents Don't Drift

The single highest-leverage move is the AGENTS.md contract. Document one way to do data access, one way to read secrets, one way to handle errors. The agent reads it and stops inventing alternatives.

Pair that with deterministic patches: repeatable code changes applied the same way every time. "Apply this pattern everywhere" beats freestyle iteration that drifts a little with each prompt.

Conventions act as rails — naming patterns, folder structure, comment markers the agent can find. And test the output: validate your schema before the agent's migration touches your database. A bad migration is a lot harder to undo than a bad function.

Beginner Mistakes in Vibe Coding SaaS

Shipping agent-written security rules unreviewed. RLS is easy to get subtly wrong.
Skipping webhook testing because "it works locally." Local doesn't retry, doesn't fail, doesn't hit real cards.
Assuming the agent handles edge cases. Consent flows, refunds, currency handling — it won't unless prompted.
Deploying before the source of truth is clear. Where does billing state actually live? If you can't answer that, you're not ready.
Not version-controlling your agent instructions. AGENTS.md is code. Treat it that way.

From Vibe to Production: Debugging Real-World Failures

The gap between "works in the demo" and "works in production" is where real vibe coding skill shows. A few failures we've actually hit and documented:

JSON-LD hydration crashes — a page that returned 200 from curl and 500 in Chrome because of source order in server-side rendering.
Canonical URL edge cases — where our blog told Google its canonical URL was localhost:3000.
Peer dependency hell — when the agent's chosen packages break your typecheck.
Webhook retry logic — agent-generated retries that hammer your own service.

None of these show up in a happy-path demo. All of them show up in production. Your testing matrix has to cover what the agent can't catch.

Building Alone vs. Building With an Agent: The Honest Comparison

Agents excel at wiring services, writing boilerplate, and applying deterministic patches. They stumble on edge cases, security review, naming things well, and testing strategy.

The time saved is real: plumbing that takes weeks compresses into a session. But you still own the architecture decisions, the security policy, and the data model. Vibe coding isn't enough for complex business logic, novel integrations, or compliance that needs legal judgment. Those are the parts you keep.

BoiledPlate as the Vibe Coding Shortcut

BoiledPlate ships the whole stack pre-built: Nuxt, Supabase, Stripe, transactional email, four languages, a prerendered Markdown blog, and SEO with JSON-LD and canonical URLs. The stack was never the hard part — the wiring is, and it's already done.

The agent interviews you, provisions your services, patches the codebase to your answers, and delivers via GitHub. The AGENTS.md contract is what lets you iterate fast without the drift. There are two tiers: Lite (free, MIT-licensed, wire it manually) and Pro (€159 one-time, lifetime updates, instant GitHub delivery).

Tools of the Vibe Coding Trade Beyond BoiledPlate

Claude Code and Cursor — agent interfaces with different strengths; either can run the workflow.
Supabase — RLS is agent-friendly once you document the rules.
Stripe — webhooks are the contract between your code and billing state. See how to set up subscriptions on this stack.
Resend — transactional email your agent-built app can rely on.
GitHub — the invite itself can be the product, provisioned by webhook the moment payment clears.

For the underlying models, Anthropic's own guidance on agentic coding is worth reading.

Testing and Confidence: How to Know It Actually Works

Let the agent write unit tests. You design the integration tests — they're where the real risks live. Verify webhook delivery with Stripe's CLI. Simulate refunds, plan changes, and currency edge cases. Run a security audit: RLS, secrets, CORS, authentication. Stripe's testing documentation covers the payment scenarios agents routinely skip. And load-test, because agents ignore it — it's not a "feature."

The Vibe Coding Workflow That Actually Ships

Session 1: interview, architecture, service provisioning.
Session 2: feature definition — agent writes, you review.
Session 3: edge cases, security, error handling.
Session 4: deployment, monitoring, a runbook.

Each gate gives you clarity before the next. That beats freestyle iteration, where the rework all lands at the end.

Beyond the First App: Scaling Your Vibe-Coded SaaS

Updates arrive as semantic, agent-readable release notes and opt-in patches — no merge hell over code you customized. AGENTS.md doubles as onboarding for new teammates, human or agent. Expect drift after week two, and maintain your instructions like any other part of the codebase. Eventually you'll hit the handoff point — complex logic where you take the wheel. Recognizing that moment is the last skill a good vibe coder learns. Read more on the BoiledPlate blog.