SaaS product development: a multi-tenant platform with billing, roles and analytics
SaaS product development that keeps working as your customer base grows, with no rewrite after the first sales. We build and run the Happ SaaS platform ourselves, with companies, plans and AI agents, so we know where these products break.
What hurts
SaaS product development with AI quickly runs into things a demo never shows. Each customer’s data has to stay isolated. Plans, trials, usage limits, refunds. Every customer wants their own roles.
AI features cost money on every request. Without cost tracking, one heavy user on a cheap plan eats the margin. You find out from the model provider’s invoice.
The first code was written fast to show investors. Now every new feature breaks two old ones. Customers see the bugs before the team does.
What we build
- Discovery: customer segment, pricing model, roles and a success metric
- Multi-tenant architecture with data isolation per company
- Subscriptions, trials, card billing through a payment provider, invoices and EU VAT handling
- Roles and team invitations, sign in with Google and SSO
- AI features with per customer cost tracking and plan limits
- Background jobs and long running workflows on Temporal
- An admin panel for your team: customers, plans, support, product analytics
- Automated tests, CI/CD, monitoring and alerts before launch
What you get
- A SaaS product in production with working billing
- Source code with IP assigned to you by contract
- An admin panel and a dashboard of product and revenue metrics
- Architecture and public API documentation
- Configured monitoring, alerts and an incident response plan
How we measure the result
- Trial to paid conversion
- AI cost per paying customer
- Monthly customer churn
- Number of incidents customers notice before the team does
Systems and stack
Industries
Questions
How much does SaaS product development cost?
From $20,000. The price depends on the pricing model and billing, the number of roles and modules, AI features, integrations and security requirements. After discovery you get a fixed estimate within 2-3 days. Model and hosting costs are separate, and we show you a forecast per customer.
How long does it take to build a SaaS?
Usually 12-24 weeks to a launch with billing. The first version opens to a small group of customers to test billing and load. You get weekly demos and can change priorities.
How do you keep AI costs under control?
We track the cost of every request and every customer. We set limits per plan, cache repeated requests and use a cheaper model where quality holds. For some tasks our own vLLM can replace a paid API.
Can it bill customers in the EU and Ukraine?
Yes. We connect a payment provider that takes EUR and USD cards for international customers, and Ukrainian acquiring such as PrivatBank or monobank for hryvnia. Invoices, VAT and refunds follow your legal setup. Billing logic is covered by tests, because mistakes here cost money and trust.
What about customer data security?
Company data is isolated at the database level and checked by tests. Secrets are kept apart from the code, and access is logged. We operate under ISO/IEC 27001:2022 and sign GDPR data processing agreements. That helps you pass enterprise customer reviews.
What happens after launch?
A SaaS needs continuous work. You can take a development retainer or SLA support. Or your team carries on: code, documentation and access are all yours.
Related services
More in this section
Describe the task. We reply within one business day, the first call is with the founder.
Describe the task. The first call is with the founder.
We reply within one business day. 30 minutes to tell you whether it is worth doing and what it costs.