Head to head
Flagsmith vs PostHog
As a feature flag API, PostHog rates higher on the APIbenchmarks Index, 85.3 to 79.1, a 6.2-point gap. Here is how they compare on each criterion.
Criterion by criterion
| Criterion | Flagsmith | PostHog |
|---|---|---|
| Documentation & DX | ||
| Reliability | ||
| Ecosystem & SDKs | ||
| Accessibility | ||
| APIbenchmarks Index | 79.1 | 85.3 |
Specifications
| Flagsmith | PostHog | |
|---|---|---|
| Best for | Open-source, self-hostable feature flags + remote config | All-in-one product analytics with built-in flags |
| Free tier | Free cloud: 50k requests/mo, 1 seat, unlimited flags (self-host fully free) | First 1M flag-eval requests/mo free, no credit card |
| Pricing | Per request (API calls) | Per request (volume-tiered) |
| Official SDKs | 12 languages | 12 languages |
Is Flagsmith better than PostHog?
On the APIbenchmarks Index, PostHog rates higher (85.3 vs 79.1). It leads on the four weighted criteria, but price is reported separately, so the best choice still depends on your budget.
Verdict in one line
PostHog leads by 6.2 points (85.3 vs 79.1) and wins 3 of 4 criteria.
Winner by criterion
| Criterion | Winner | ||
|---|---|---|---|
| Documentation & DX | 78 | 88 | |
| Reliability | 74 | 82 | |
| Ecosystem & SDKs | 80 | 80 | Tie |
| Accessibility | 86 | 92 |
Choose Flagsmith if… / choose PostHog if…
- →your use case matches its focus: open-source, self-hostable feature flags + remote config
- →documentation & dx matters most to you (88 vs 78)
- →reliability matters most to you (82 vs 74)
- →accessibility matters most to you (92 vs 86)
- →your use case matches its focus: all-in-one product analytics with built-in flags
Pricing side by side
- Model
- Per request (API calls)
- Free tier
- Free cloud: 50k requests/mo, 1 seat, unlimited flags (self-host fully free)
- Free$0
- Start-Up$40-45/mo
- Scale-Up$250-300/mo
- EnterpriseCustom
- Open Source (self-hosted)Free
- Model
- Per request (volume-tiered)
- Free tier
- First 1M flag-eval requests/mo free, no credit card
- Free$0/mo
- Pay-as-you-go (1-2M tier)$0.0001 / request
- Pay-as-you-go (2-10M tier)$0.000045 / request
- Pay-as-you-go (10-50M tier)$0.000025 / request
- Pay-as-you-go (50M+ tier)$0.00001 / request
Vendor-published pricing, verified 2026-06-27 (Flagsmith) and 2026-06-27 (PostHog).
SDK and language coverage
Both · 6
PythonNode.jsJavaPHPRubyGo
Only Flagsmith · 6
JavaScriptReact / React NativeFlutterSwift/iOSKotlin/Android.NET / C#
Only PostHog · 6
Web / JavaScriptRust.NETiOSAndroidReact
Strengths and weaknesses
- +Fully open-source (BSD-3) core that can be self-hosted with no request limits or per-seat fees
- +Broad official SDK coverage: 15+ client- and server-side languages/platforms
- +Genuinely usable free SaaS tier (50k req/mo) plus low Start-Up pricing vs LaunchDarkly
- –No built-in experimentation stats engine; needs Amplitude/Mixpanel/Statsig to determine winners
- –Lacks advanced safety features like automated rollbacks and guardrail-metric monitoring
- –On-prem/private hosting and SCIM/LDAP gated behind custom-priced Enterprise tier
- +Generous free tier, first 1M flag-evaluation requests per month are free with full feature access and no credit card
- +Server-side local evaluation cuts flag latency from ~500ms to 10-50ms by removing network I/O
- +Flags are natively wired into PostHog analytics, experiments, and session replay, no event export needed to measure flag impact
- –Reliability has wobbled, four flag-service incidents in late Oct 2025 totaling 14+ hours of major impact (CPU under-sizing root cause)
- –Dense, technical UI with a real learning curve for designing flags, cohorts, and experiment variants
- –Documentation is strong for getting started but thin for advanced flag debugging scenarios
Flagsmith vs PostHog: questions
- Which has better documentation, Flagsmith or PostHog?
- PostHog scores higher on documentation and developer experience: 88 vs 78 out of 100.
- Which is more reliable, Flagsmith or PostHog?
- PostHog scores higher on reliability: 82 vs 74 out of 100.
- Do Flagsmith and PostHog have a free tier?
- Flagsmith: yes (Free cloud: 50k requests/mo, 1 seat, unlimited flags (self-host fully free)). PostHog: yes (First 1M flag-eval requests/mo free, no credit card).
- How are Flagsmith and PostHog priced?
- Flagsmith: Per request (API calls). PostHog: Per request (volume-tiered).
- Which has more official SDKs?
- Both list 12 official SDKs.