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Flagsmith vs PostHog

Flagsmith logo

Flagsmith

Software

Open-source feature flag and remote config platform

From
Free
Rated
-
Full reviewWebsite
PostHog logo

PostHog

Software

The single platform to analyze, test, observe, and deploy new features

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Flagsmith the Free plan supports only a single team member, limiting collaboration for small teams.; PostHog the free tier covers 1M events, 5K web session recordings and 2.5K mobile recordings per month before usage-based billing starts
  • They diverge on capability: Flagsmith covers Segments, PostHog covers Product analytics.

Where they differ

Only the attributes on which Flagsmith and PostHog actually diverge.

Attributes where Flagsmith and PostHog differ
AttributeFlagsmithPostHog
Pricing modelfreemiumusage-based
Platformsweb, apiWeb, Ios, Android, Api
FoundedUnknown2020

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Unknown).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Flagsmith

  • Segments
  • Scheduled flags
  • SDKs
  • SAML/SSO

Only in PostHog

  • Product analytics
  • Session recording
  • Heatmaps
  • SQL access
  • Data warehouse
  • Apps platform
  • Slack
  • Microsoft Teams

Both cover

  • Feature flags
  • A/B testing

What people use each for

The jobs each tool is most often brought in to do.

Flagsmith

  • Gradual feature rollouts across environmentsnot PostHog
  • Remote configuration without redeploying codenot PostHog
  • Running A/B tests tied to feature flagsnot PostHog
  • Self-hosting feature flags for data residency requirementsnot PostHog

PostHog

  • Product analyticsnot Flagsmith
  • Feature experimentationnot Flagsmith
  • User behavior trackingnot Flagsmith
  • A/B testingnot Flagsmith
  • Debug production issuesnot Flagsmith

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Flagsmith

  • The Free plan supports only a single team member, limiting collaboration for small teams.
  • Exceeding request limits triggers overage charges after a one-time 30-day grace period.
  • Enterprise-grade SSO and governance are locked behind the Scale-Up and Enterprise tiers.
  • Self-hosting requires operating and updating the platform yourself, unlike a fully managed SaaS competitor.

PostHog

  • The free tier covers 1M events, 5K web session recordings and 2.5K mobile recordings per month before usage-based billing starts
  • Accounts without a card on file are limited to 1 project; adding one raises it to 6
  • Data retention is 1 year until a card is added, which extends it to 7 years
  • Support is community-only until the account is on a paid plan
  • Error tracking is capped at 100K exceptions and surveys at 1500 responses per month on the free tier

Pricing, plan by plan

Flagsmith

Free
  • FreeFree
    • Up to 50,000 requests/month
    • 1 team member
    • Unlimited feature flags, environments, identities and segments
  • Start-Up$45/month
    • Up to 1,000,000 requests/month
    • 3 team members
    • Scheduled flags, 2FA, A/B testing, integrations, email support
  • Scale-Up$300/month
    • 5,000,000+ requests/month
    • 5-20 team members
    • SAML/SSO, governance features, priority support

PostHog

Free
  • FreeFree
    • 1M events/month
    • 5K sessions/month
    • Unlimited users
  • Paid$undefined/month
    • $0.00031/event
    • $0.005/session
    • Advanced permissions
  • Enterprise$undefined/month
    • SAML SSO
    • Advanced security
    • Dedicated support

Which should you pick?

Choose Flagsmith if

  • You need segments.
  • You want to start without paying.
  • You work on web, api.
  • You also want scheduled flags.
Flagsmith review

Choose PostHog if

  • You need product analytics.
  • You want to start without paying.
  • You work on Web, Ios, Android, Api.
  • You also want session recording.
PostHog review

Questions people ask

Is Flagsmith or PostHog better?
Neither clearly leads. Flagsmith starts at Free and PostHog at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Flagsmith or PostHog?
Flagsmith starts at Free and PostHog at Free.
Does Flagsmith or PostHog run on more platforms?
Flagsmith runs on web, api. PostHog runs on Web, Ios, Android, Api.
Can I use Flagsmith for free?
Both have a free tier, so you can try either at no cost before committing.
What is Flagsmith best used for?
Flagsmith is most often used for gradual feature rollouts across environments, remote configuration without redeploying code, running a/b tests tied to feature flags, self-hosting feature flags for data residency requirements. Of those, gradual feature rollouts across environments and remote configuration without redeploying code are not what PostHog is typically brought in for.
What can Flagsmith do that PostHog cannot?
Flagsmith covers Segments, Scheduled flags, SDKs, SAML/SSO. PostHog covers Product analytics, Session recording, Heatmaps, SQL access. Both handle Feature flags, A/B testing.

Answered from the vendors’ own pages

Flagsmith: What does Flagsmith cost?

Flagsmith has a Free plan, a Start-Up plan from $40-45/month, a Scale-Up plan from $250-300/month, and custom Enterprise pricing.

Source
Flagsmith: Is there a free plan, and what are its limits?

The Free plan supports up to 50,000 requests per month and 1 team member, with unlimited feature flags, environments, identities and segments.

Source
Flagsmith: How is usage metered?

Usage is metered by monthly API requests; exceeding a plan's limit triggers overage charges starting around $50 per million requests, with a 30-day grace period the first time a paid plan exceeds its limit.

Source
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