TL;DR
Feature flags control who sees what features (deployment tool). A/B testing tools measure which version performs better (optimization tool). They're complementary: use feature flags for safe rollouts, A/B testing for conversion optimization. Many modern tools (PostHog, Statsig) combine both.
Key Differences
| Aspect | Feature Flags | A/B Testing |
|---|---|---|
| Primary purpose | Control feature rollout | Measure impact on metrics |
| Statistical analysis | Usually no | Yes, built-in |
| Visual editor | No | Often yes |
| Requires code | Yes | Not always |
| Use case | Safe deployments | Conversion optimization |
When to Use Each
| Scenario | Use | Why |
|---|---|---|
| Testing headline copy | A/B Testing | Visual change, need conversion data |
| Rolling out new feature | Feature Flags | Gradual rollout, kill switch |
| Testing pricing page | Both | A/B test with feature flag for safety |
| Canary deployment | Feature Flags | Technical rollout, not conversion focused |
Tool Categories
A/B Testing Only
- • ExperimentHQ
- • VWO
- • Convert
Feature Flags Only
- • LaunchDarkly
- • Flagsmith
- • ConfigCat
Both
- • PostHog
- • Statsig
- • GrowthBook
Our Recommendation
For conversion optimization: Use ExperimentHQ. Visual editor, statistical analysis, $29/month.
For feature rollouts: Add LaunchDarkly or use PostHog/Statsig for both.