- Your first Project and file uploads
- The major AI families to try the workflow
- A small daily message allowance
Build a SaaS with AI
Build a SaaS with AI: from the MVP to the first paying subscriber.
A SaaS is a specific kind of software business: people pay every month, so it has to keep working, keep their data safe, and keep being worth it. That adds a short list of things a one-off tool does not need: accounts, billing, a database that survives, a pricing page, and a way to know when something breaks. This page is the build order for one person with AI, with the pieces that are easy to get wrong marked.
Free to start. The latest models matter most for the review of auth, billing and data code.
The build order
Eight pieces, in the order that keeps you shipping
The one job (the MVP)
One screen that does the one thing. No settings, no dashboard, no team features. If people will not pay for the one job, they will not pay for the dashboard. Cutting the scope has its own page.
Accounts and sign-in
Use a hosted provider (Supabase Auth, Firebase Auth, Clerk). Never store passwords yourself. Have a second model review the sign-in flow for the usual holes: session handling, password reset, what a logged-out user can still reach.
A database that survives
Postgres through a hosted service is the safe default. Ask for the schema before the code, and ask specifically about backups, exports and what happens when two users edit the same thing.
Billing
Stripe for web. Subscriptions, trials, cancellation, failed payments, refunds. The webhook that updates a customer's plan is the most common place for a double-charge bug; make idempotency the first review question.
The pricing page
One or two plans, monthly and yearly, what is included, the FAQ under it. Draft it from the customer research in the Project, and have a second model read it as a sceptical buyer.
Deploy with a checklist
Environment variables, secrets out of the code, error reporting, uptime alert, a rollback plan. You deploy with your own provider; the checklist comes from the Project.
The first ten subscribers
The people from validation, the communities you chose, a launch post that leads with the problem. See launching.
The loop
Support emails, cancellations and usage numbers go back into the Project weekly. Fix the top reason people leave before adding anything new.
The dangerous parts
Four places SaaS code goes wrong, and the review question for each
| Area | Typical failure | Ask a second model |
|---|---|---|
| Billing webhooks | A retried event applies twice: double charge, or a plan downgrade re-applied after an upgrade. | "What happens if this webhook is delivered twice, or out of order?" |
| Auth and sessions | A logged-out user can still hit an API route; a password reset link that never expires. | "List every route and what an unauthenticated user can do with it." |
| Multi-tenancy | One customer can see another customer's rows because a query forgot the account filter. | "Show me every query and confirm each is scoped to the current account." |
| Data migrations | A schema change that loses data in production, tested only on an empty database. | "What does this migration do to existing rows, and how do I roll it back?" |
Why two models
These are exactly the bugs a single model writes and then approves. Sending the same file to a second model with the same Project context catches most of them before a customer does. The full list is on coding with AI.
Pricing a SaaS
Three questions that decide the price
What does it replace? If it saves a customer four hours a month of paid work, $29 is easy to justify; price against what they pay today, not against your costs.
Monthly, yearly, or both? Yearly with a discount improves cash and lowers churn; monthly lowers the barrier. Offer both, lead with yearly on the page.
Free trial or free tier? A trial suits tools with a fast first win. A free tier suits tools that get better with use and need people to build up data before they pay. Ask several models to argue it for your specific product, then test one.
Free is the start. The latest models are the difference.
Billing, auth and data code is where a wrong answer costs real money.
A double charge, a leaked account or a lost table is a refund, a support crisis or the end of the business. The latest models find these problems in review far more reliably than older ones, and hold the whole codebase in view while they do it. For a SaaS, the paid plans are cheaper than one bad webhook.
Newer models hold your whole Project in view instead of the last few messages, reason through trade-offs instead of picking the first plausible answer, and are wrong less often and with less confidence. For the questions on this page, that is the difference between advice that sounds right and advice you can act on.
Pro from $20 a month, cancel any time. The free plan stays free.
- The latest ChatGPT, Claude, Gemini, Grok and Perplexity models, all on the same Project
- Far more messages a day, so a working session does not stop halfway
- Modes where several models draft, challenge and verify each other's answers
- Larger uploads and GitHub import so the whole codebase is in context
- Independent verification passes for library and API facts
Start here
First messages for a SaaS Project
Add the spec, the customer research, and the repo where enabled. Then start here.
ScopeCut this spec to the one job a customer would pay for monthly. List everything you removed and why.
SchemaDesign the database schema for this app, scoped per account. Then tell me how backups, exports and concurrent edits work.
BillingImplement subscriptions with Stripe: trial, cancel, failed payment, refund. Then review the webhook handler for double delivery and ordering.
Auth reviewList every route in this app and what an unauthenticated user can do with it. Fix anything that should be protected.
Pricing pageWrite the pricing page from the customer research in this Project: two plans, monthly and yearly, and the FAQ a sceptical buyer would need.
ChurnHere are this month's cancellations and support emails. Group by cause, rank, and tell me the one thing to fix before adding features.
Honest answers
What people ask
Can one person build a SaaS with AI?
Yes, for a focused product. The code is the smaller part; accounts, billing, reliability and support are the rest, and this page is the order to do them in. Use hosted providers for anything involving passwords or cards.
Which stack should I use?
Whatever the framework starters support well and your AI knows deeply: a React or Next.js front end, hosted Postgres, hosted auth, Stripe. Boring choices are the fast ones for a first SaaS.
How do I avoid the double-charge bug?
Store every processed webhook event ID and skip duplicates; handle events out of order. Ask a second model to review the handler with exactly those two questions.
When should I add a team plan?
When three customers ask for it. Not before. Multi-user features multiply the bugs and the support.
Does MultipleChat host or deploy my SaaS?
No. It plans, writes, reviews and explains; you deploy with your own provider so nothing depends on anyone else.
What is free?
Your first Project, file uploads and the major model families. The latest models, larger uploads and GitHub import are on paid plans. See plans.
Start with the one job. Add billing when someone asks to pay.
Put the spec in a Project, cut it to one screen, and have a second model review everything that touches money or accounts. Free to start.
Also: create an MVP with AI · build software with AI · coding with AI · launch it