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Case study · 2026 · Open source

SaaS Starter — production-ready full-stack SaaS foundation

An open-source Next.js starter kit that ships authentication, subscription billing and a protected dashboard out of the box, so teams can invest their time in the product rather than the plumbing.

Type

Open-source product

Role

Product design & full-stack development

Stack

Next.js, PostgreSQL, Prisma, Auth.js, Stripe

Source

View on GitHub ↗

SaaS Starter landing page

01 — Overview

The brief

Almost every SaaS product begins by rebuilding the same foundations: sign-up and sign-in, recurring payments, account management and a secure application shell. This work is costly, error-prone and rarely a competitive advantage.

The objective was a reusable, well-tested foundation that handles these concerns correctly — including the difficult edge cases — behind a clean, easily rebranded interface.

02 — Challenge

Key considerations

  • Billing correctnessStripe retries webhooks and does not guarantee order; subscription state must never drift.
  • Security by defaultProtected routes, hashed credentials, validated input and rate-limited public endpoints.
  • Operational readinessClear failures on misconfiguration and guidance for serverless database pooling.
  • Developer experienceA fast, documented setup that a new team can run and extend within minutes.
Feature highlights and pricing plans
Marketing page — feature highlights and a three-tier pricing model.

03 — Solution

What was delivered

  • AuthenticationAuth.js v5 with email/password and Google OAuth, bcrypt hashing and proxy-level route protection.
  • Subscription billingStripe Checkout and Customer Portal across Free, Pro and Team plans.
  • Idempotent webhooksEvents recorded transactionally and ordered by timestamp, so retries and late deliveries cannot corrupt state.
  • AI assistantAn optional Claude-powered streaming chat widget with rate limiting and bounded input and output.
  • Product analyticsOptional PostHog integration with user identification and sign-up tracking.
  • Quality gatesStartup environment validation, Vitest tests, linting, type-checking and CI on every pull request.
Dashboard in light mode
Dashboard in dark mode
Protected dashboard — light and dark themes, following the user's system preference.
Sign-in page
Billing and plan management
Authentication and billing — sign-in with email or Google, and self-serve plan upgrades.
Mobile — landing Mobile — features Mobile — dashboard Mobile — billing
Fully responsive — every screen designed for mobile as well as desktop.

04 — Outcome

The result

SaaS Starter provides a production-minded foundation that shortens time to launch for new products. Authentication, payments and the application shell are in place from day one, with the reliability and security details already addressed — leaving teams free to focus on the features that differentiate their product.

  • Next.js 16
  • React 19
  • TypeScript
  • PostgreSQL
  • Prisma
  • Auth.js v5
  • Stripe
  • Tailwind CSS
  • shadcn/ui
  • Claude API
  • PostHog
  • Vitest
  • GitHub Actions
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