Build a SaaS MVP from an idea to a live product
Most SaaS ideas die in setup, not in the idea itself — auth, billing, and deploy eat the weeks that should've gone to the actual feature.
Posted by @sarihammad
A live SaaS MVP — real auth, real subscription billing, deployed to production — built from a single scoped idea instead of stalling in setup. Budget a focused weekend to a week, most of it spent on the one core feature rather than the infrastructure around it.
Most SaaS ideas don't die from a bad idea, they die from setup sprawl — auth, billing, and deploy each becoming their own multi-week side quest instead of infrastructure to get through quickly. This workflow runs the setup in the order that keeps it fast: scope ruthlessly first, then auth, then billing, then deploy, then spend the time you saved on the one feature that actually matters.
Turn the idea into a one-sentence MVP scope
Force ruthless scoping before any setup work begins, so the MVP stays buildable in days, not months.
Fill in
My SaaS idea: {{idea}}
Help me scope this into a true MVP: what's the single core feature that has to exist for someone to get real value from this, and what should I explicitly defer past launch? Push back if my "MVP" is still trying to do too much — I want something buildable in days, not months, with everything else deferred.Why it works
Naming exactly one core feature, and explicitly deferring everything else, is what keeps an MVP from quietly growing into a full product before it's ever shipped — the temptation to add "just one more thing" is exactly what turns a weekend build into a months-long project that never launches.
Checkpoint
You have one specific core feature named, and an explicit list of what's deliberately deferred past launch.
Common mistakes
- ×Scoping in "and also" additions instead of committing to one core feature.
- ×Deferring so aggressively that the MVP no longer delivers real value to anyone.
Pick a minimal stack and scaffold the project
Choose a stack sized to the MVP, then get a running project instead of researching options indefinitely.
Fill in
Scoped MVP: {{mvp_scope}}
My familiarity: {{familiarity}}
Recommend a minimal stack for this specific MVP — default to Next.js on Vercel, Clerk for auth and billing, and a managed Postgres (Neon or Vercel Postgres) unless something about this idea genuinely needs a different shape, and tell me honestly if it does. Then give me the exact scaffolding commands to get a blank project running locally.Why it works
Defaulting to a known-good, well-integrated stack instead of evaluating every option is what prevents the classic trap of spending the MVP's entire time budget on stack research instead of the product — this stack is default not because it's the only good option, but because it's fast to stand up and hard to get stuck in.
Checkpoint
You have a scaffolded project running locally, with a stack decision made and not still open.
Common mistakes
- ×Spending days evaluating stack alternatives instead of defaulting to a known-good option and moving on.
- ×Picking a stack based on what's trendy rather than what's fastest to actually ship this specific MVP.
Add authentication with Clerk
Get real user accounts working before building anything that depends on knowing who's using it.
Walk me through adding Clerk authentication to this scaffolded project: installing the SDK, wrapping the app in the provider, protecting the routes that need a signed-in user, and adding sign-in and sign-up UI. Give me the exact files to create or edit and the exact code, not a general description — I want this actually working, not just explained.
Why it works
Requiring exact files and code, not a general description, is what turns this step into something actually done rather than something vaguely understood — auth is foundational enough that "I get the idea" isn't the same as a signed-in user actually existing in the running app.
Checkpoint
You can sign up, sign in, and sign out in the running app, and a protected route actually redirects a signed-out visitor.
Common mistakes
- ×Accepting a conceptual explanation of Clerk instead of actually wiring it into the running project.
- ×Protecting the app's routes inconsistently, leaving some pages accessible without signing in by accident.
Add subscription billing with Clerk Billing
Get a real paid tier working, gated correctly, before assuming monetization can wait.
Fill in
My rough pricing: {{pricing}}
Walk me through adding Clerk Billing to charge for this MVP: enabling billing on the instance, defining a single paid plan at this price, gating the core feature behind it with a real server-side check (not just hiding a button), and rendering the pricing table. Flag anything that needs a real, verified Stripe account connected before it'll actually process payments, versus what works in test mode.Why it works
Requiring a real server-side gate, not just a hidden button, is what prevents the common mistake of monetization that's cosmetic — a determined free user hitting the API directly should hit a real 403, not just a UI that happens to hide the upgrade prompt.
Checkpoint
A real paid plan exists, the core feature is gated by a server-side check, and you know specifically what still needs a verified Stripe account before real payments work.
Common mistakes
- ×Gating a feature only in the UI, leaving the actual API route open to anyone who calls it directly.
- ×Assuming test-mode billing means real payments already work, and discovering the gap only at actual launch.
Deploy to Vercel and connect a domain
Get a real, live production URL, not just a working local build.
Fill in
Custom domain, if any: {{domain}}
Walk me through deploying this project to Vercel for the first time: connecting the repo, setting the required environment variables for Clerk and the database in the Vercel project settings (not just locally), promoting the deploy to production, and connecting the domain if I have one. Call out anything that behaves differently between a preview deploy and the real production one.Why it works
Explicitly distinguishing preview from production deploys catches a specific, common failure — environment variables set locally or on a preview deploy don't automatically exist on production, and discovering that gap after telling people the site is live is a bad way to find out.
Checkpoint
You have a live production URL where signing up, signing in, and the core feature all actually work — not just a preview deploy.
Common mistakes
- ×Testing only on a preview deploy and assuming production is configured identically.
- ×Forgetting to set required environment variables in the Vercel project settings, not just locally.
Ship the core feature end to end and run a launch checklist
Finish the one feature that actually matters, then verify the whole path works before telling anyone it exists.
Given everything set up so far, help me build the single core feature from the original MVP scope, end to end. Once it's built, give me a launch checklist: what to personally verify works (sign-up, billing, the core feature, in that order) before telling anyone this exists, and what's genuinely fine to leave rough for a first version rather than polish before launch.
Why it works
Checking sign-up, billing, and the core feature in that specific order mirrors the actual path a first real user takes — verifying them in a different order can miss a break in the sequence itself, like a paid feature that works fine when tested as an already-subscribed account but breaks for someone subscribing for the first time.
Checkpoint
You've personally walked through sign-up, billing, and the core feature in order on the live production URL, and have a short, deliberate list of what's fine to leave rough.
Common mistakes
- ×Testing each piece in isolation instead of walking the actual end-to-end path a first user would take.
- ×Polishing rough edges indefinitely instead of shipping once the core path actually works.
Follow-ups
- The end-to-end walkthrough broke at this step: {{broken_step}}. Help me fix it.
- I got my first real signup — help me figure out what to build or fix next based on how they're actually using it.