Achromatic

Achromatic is the go-to SaaS Starter Kit for web apps, packed with features like advanced auth, billing, multi-tenancy, emails, user profiles, onboarding, API keys and webhooks. Built for Next.js, Auth.js, shadcn/ui and Tailwind, it saves months of development time so you can focus on building your business/product. For $180, you get lifetime access to a modern stack with Next.js 15, React 19 and TypeScript. Achromatic is updated daily and includes a variety of application components to extend functionality.