A/B Testing

GrowthBook is an open-source feature flagging, A/B testing, and product analytics platform. It helps teams safely release features, run experiments, and measure results. Free tier: 3 users, 1 project, unlimited flags and experiments, 1M events/month, 1M CDN requests/month, and 5GB bandwidth. No credit card required. Self-hosted version supports unlimited users and API requests.

Statsig is a product development platform offering feature flags, A/B testing, experimentation, product analytics, and session replay. Free tier: 2 million events/month, unlimited feature flag checks and seats, 50,000 session replays/month, and 1-year analytics retention. No credit card required. Exceeding the event limit disables metric-lift calculations, but feature flags continue working.

Optimizely is a digital experience platform that enables businesses to experiment, personalize, and optimize their digital products and experiences. It provides tools for A/B testing, content management, feature flagging, and customer data management.

Qonversion is a subscription management platform offering in-app purchase tracking, revenue analytics, A/B testing, paywall optimization, and cross-platform subscription management. Free tier: Free up to $7,000 in monthly tracked revenue, including all features, unlimited apps and users, analytics, and integrations. No credit card required. Above $7,000, charges 0.8% of total tracked revenue.