---
title: "SaaS Product Development: Kensink Labs"
description: "SaaS product development from a senior lab: multi-tenancy, billing, auth, and roles built in from day one. Full source ownership in eight weeks."
source: "https://www.kensink.com/services/saas-product-development/"
canonical: "https://www.kensink.com/services/saas-product-development/"
---
★ SaaS product development Project Types 8-week engagement

PROJECT TYPE · SAAS PRODUCTS

# SaaS product development. Multi-tenancy, billing, RBAC, from day one.

Multi-tenancy, billing, auth, and roles are the parts that are painful to retrofit. We build them in from the start so your SaaS can onboard customer number two without a rewrite.

Next.js PostgreSQL Payment API OAuth

[Start a conversation →](https://www.kensink.com/contact) [All project types →](https://www.kensink.com/services)

Cycle

8 weeks · fixed price

Stack

Next.js + Postgres

Output

Production code + eval suite

Handoff

Full source ownership

\[THE SHORT VERSION\]

## The SaaS basics are the parts teams underestimate.

Every SaaS needs the same foundation: tenant isolation, authentication, role-based access, subscription billing, and usage limits. These are deceptively hard and brutal to add later. We build the foundation deliberately up front, so feature work sits on solid ground instead of fighting it.

When it fits

-   B2B or B2C subscription products
-   Multi-tenant apps serving many organizations
-   Products that will need billing, roles, and onboarding

When it does not

-   Single-customer internal tools
-   A quick validation MVP (start there, then grow into SaaS)

\[HOW WE BUILD IT\]

## How we build with SaaS product development.

01

### Tenancy and auth first

We decide the multi-tenant model and wire auth and roles before features. Isolation is enforced at the data layer, not hoped for.

02

### Billing as a state machine

Subscriptions, plans, and usage handled with idempotent payment flows that reconcile. Money has to tie out.

03

### Feature work on solid ground

With the foundation in place, product features ship fast and safely on a typed, tested base.

04

### Ship and hand over

Deployed with monitoring and onboarding flows, handed over with full source ownership and a 90-day warranty.

\[ WHAT YOU GET \]

## What the engagement leaves behind.

Day 1

Multi-tenant and billable

0

Cross-tenant data paths

100%

Source ownership at handoff

8 wks

Problem to production

\[COMMON QUESTIONS\]

## Questions we get asked.

Should I start with an MVP or a full SaaS?

Usually an MVP to validate demand, then grow into a full multi-tenant SaaS. We build the MVP so the path to SaaS is an extension, not a rewrite. See our MVP engagement for the lighter starting point.

How do you handle billing?

Stripe (or your processor) behind a clean abstraction, with idempotent capture, plan changes, proration, and reconciliation. We treat billing as a state machine with an audit trail, the same way we treat payments in production.

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[View .md](https://www.kensink.com/services/saas-product-development.md)

\[RELATED\]

## Worth a look next.

[

Design Patterns

Multi-tenant SaaS

Read more

](https://www.kensink.com/patterns/multi-tenant-saas)[

Technologies

Stripe & Payments

Read more

](https://www.kensink.com/technologies/stripe-payments)[

Project Types

MVP development

Read more

](https://www.kensink.com/mvp)

APPLIED K-FRAMEWORK

## Bring the problem.  
We’ll bring the build.

Senior engineers, eval suite at handoff, full source ownership. Sprint, program, or ongoing. We shape the engagement to the work.

[Start a conversation →](https://www.kensink.com/contact) [Read the K-Framework](https://www.kensink.com/k-framework)