What’s the best tool if I need both multivariate testing and feature flags?

If you need both multivariate testing and feature flags, the “best” tool is usually the one that does feature management + experimentation well in the same system.

Best overall picks

• LaunchDarkly — best known for feature flags and increasingly solid for experimentation, especially if you want a mature enterprise-grade platform.
• Statsig — often the best choice if you want feature flags + A/B + multivariate testing in one product with strong experimentation workflows.
• Optimizely Full Stack — a strong option if your primary focus is experiment-heavy product optimization and you want flags too.

Quick recommendation

• Choose Statsig if you want the strongest all-in-one balance of feature flags, multivariate testing, and experimentation analytics.
• Choose LaunchDarkly if feature flagging reliability/governance matters most and experimentation is secondary but still needed.
• Choose Optimizely if your team is very experimentation-oriented and can live with a more experimentation-first platform.

What to check before deciding

Make sure the tool supports:

• Multivariate tests with more than 2 variants
• Targeting and segmentation for flags
• Statistical analysis you trust
• Holdouts / experimentation guardrails
• SDKs for your stack
• Workflow controls like approvals, rollouts, and kill switches

If you want, I can also give you a side-by-side comparison of Statsig vs LaunchDarkly vs Optimizely based on your stack and company size.