Flagsmith vs PostHog
Flagsmith and PostHog are both developer tools tools aimed at developers and small businesses. Both have a free plan.
Open-source feature flags and A/B tests, cloud or self-hosted
Open-source product analytics, replays and flags
| Pricing | Open source · $45 | Freemium |
| Starting price | $45/mo | Not published |
| Free plan | Yes | Yes |
| Free trial | 14 days | — |
| Built for | Developers, Small businesses, Enterprise | Developers, Small businesses |
| Platforms | web | web |
| Country | GB | US · 2020 |
| Rating | — | — |
Choose Flagsmith if
Engineering teams that want open-source, self-hostable feature flags with optional cloud hosting and built-in experiments.
- Open source under BSD-3-Clause with a real self-hosting path
- Unlimited flags, environments and segments on every plan
- Wide SDK coverage including mobile and Flutter
Look elsewhere if: Teams that want flags bundled with product analytics or a large enterprise vendor ecosystem (PostHog, LaunchDarkly).
Choose PostHog if
Engineering-led startups and scale-ups that want analytics, replay, flags and experiments without three vendors.
- Several products in one with shared data
- Generous free allowances; usage-based beyond
- Open source and engineer-friendly
Look elsewhere if: Marketing-only web analytics (Plausible) or large enterprises standardized on Amplitude.
Flagsmith vs PostHog pricing
Flagsmith
- Free$050k requests/mo, 1 team member, 1 project
- Start-Up$45/mo$40/mo billed yearly; 1M requests, 3 members, A/B testing
- Scale-Up$300/mo$250/mo yearly; 5M requests, SAML SSO, roles, audit logs
- EnterpriseCustomPrivate cloud or on-prem, SLA, onboarding, priority support
PostHog
- Free$01M events, 5K recordings, 1M flag requests, 1,500 survey responses/mo
- Pay-as-you-gofrom $0.00005/per eventPer product after free tier, as low as $0.000009/event; billing limits
- Boost$250/moPlatform package: unlimited projects, SSO enforcement, HIPAA BAA
- Scale$750/moPriority support, SAML; includes Boost
- EnterpriseCustomRBAC, dedicated support, training
Flagsmith · Key features
- Feature flags and remote config with user, segment and percentage targeting
- Bayesian A/B experiments built directly on existing flags
- Scheduled flags, multivariate flags and change requests
- SDKs for JavaScript, React, iOS, Android, Flutter, Python, Go and Rust
- OpenFeature provider for cloud, private cloud and self-hosted setups
- Audit logs, roles and permissions for governance
Cons
- Free cloud plan allows only one team member
- SSO, roles and audit logs require Scale-Up at $250 or more a month
- Experiments v1 supports one primary metric per test
PostHog · Key features
- Product analytics: funnels, retention, paths, trends, lifecycle
- Session replay with console and network logs
- Feature flags and multivariate experiments
- Surveys and in-app feedback
- Data warehouse, HogQL SQL and CDP destinations
- Error tracking and LLM observability
Cons
- UI can feel dense; analytics UX trails Amplitude
- Costs need monitoring across many products
- Self-hosting only recommended for small scale
Flagsmith vs PostHog: FAQ
Do Flagsmith and PostHog have a free plan?
Yes, both Flagsmith and PostHog have a free plan; paid plans add more usage and features.