Flag — Feature Flag SaaS Starter (Percentage Rollouts)

Flag — Feature Flag SaaS Starter (Percentage Rollouts) is a no code app builder product available on the Whop marketplace, created by Toolstack and launched in September 2026.

A production-ready Next.js starter for building a feature flag service that lets you toggle features remotely and roll out to users gradually without redeploying. The rollout logic is deterministic using a tested hash function—we caught and fixed a real bug where a weaker hash made different flags statistically correlated. Build a complete SaaS with API key authentication, instant toggling, Stripe billing integration, and SQLite for local development. All the infrastructure you need: Next.js 14, Prisma ORM, NextAuth, and Tailwind CSS. - Next.js 14 starter with Prisma and SQLite - Deterministic feature flag rollout logic with tested hashing - API key authentication and rate limiting - Instant remote feature toggling without deployment - Stripe billing integration included - NextAuth for user authentication - Tailwind CSS for the UI - Unlimited projects per license - No third-party service dependencies - Full source code and documentation

Flag — Feature Flag SaaS Starter (Percentage Rollouts) has is priced at $79 (one-time payment).

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