Sinter is a production-ready Next.js starter kit built for Claude Code, designed for solo founders and small teams going from prototype to live product. It provides everything between "it works" and "it's safe to go live": pre-configured authentication, Stripe payments, transactional email, security scanning, CI/CD with 25+ automated workflows, and a token-based design system with 30+ accessible components. Unlike generic Next.js boilerplates and starter templates, Sinter includes a deep Claude Code integration layer: 20+ slash commands, 35+ specialized skills, 15+ safety hooks, and a verification protocol that prevents AI-generated bugs from reaching production. A context engineering system with 380+ micro-lessons gives Claude Code structured knowledge about your project, so your fixes stick and your patterns compound over time. Building an AI-powered product? Sinter ships with OWASP LLM Top 10 security hardening, prompt caching with 90% cost savings, multi-provider support (OpenAI and Anthropic), streaming, and rate limiting. Tech stack: Next.js 15 (React 19, App Router), Supabase (PostgreSQL, Auth, RLS), Stripe, and Claude Code. One-time purchase with lifetime updates. Best for: SaaS applications, AI-powered tools, dashboards, content platforms, and any web application where users log in and pay. Not intended for native mobile apps, static sites, or desktop applications.