TL;DR
Best tools with both A/B testing and feature flags: PostHog (best all-in-one), Statsig (best for product teams), GrowthBook (best open source). For visual A/B testing without feature flags, use ExperimentHQ. You often don't need both in one tool—use ExperimentHQ for marketing tests and add feature flags separately if needed.
Do You Actually Need Feature Flags?
Feature flags and A/B testing solve different problems:
- • A/B testing: Measure which version performs better
- • Feature flags: Control who sees what, when
If you just want to test headlines and CTAs, you don't need feature flags. If you're deploying new code features, you might.
Tool Comparison
| Tool | Price | Feature Flags | A/B Testing | Verdict |
|---|---|---|---|---|
| PostHog | Free - $450/mo | Best All-in-One | ||
| Statsig | Free - Custom | Best for Product | ||
| GrowthBook | Free (self-hosted) | Best Open Source | ||
| LaunchDarkly | $10/seat/mo | — | Flags only | |
| ExperimentHQ | $29/mo | — | A/B testing focus |
Use Case Guide
| Use Case | Needs Flags? | Why |
|---|---|---|
| Gradual feature rollout | Roll out to 10%, then 50%, then 100% | |
| A/B test a headline | No | Visual change, no code deployment |
| Kill switch for new feature | Quickly disable if issues arise | |
| Test pricing page layout | No | Visual A/B test |
| Test new checkout flow | Code change with measurement |
Our Recommendation
For marketing site A/B tests: Use ExperimentHQ. You don't need feature flags for visual testing.
For product experiments + flags: PostHog or Statsig give you both in one platform.
For open source: GrowthBook offers both capabilities self-hosted.