Statsig vs GrowthBook - The Honest Experimentation Comparison (2026)

Statsig and GrowthBook are the two experimentation heavyweights people cross-shop, and they take opposite paths to the same goal. Statsig is the managed, experiment-first platform where flag checks are free and you pay for events. GrowthBook is the open-source, warehouse-native one where your data never leaves your infrastructure. The comparison comes down to whether you want a polished managed product or open source and data control - and whether you already run a data warehouse.

I’ve read both tool pages. Here’s the honest, use-case comparison, with PostHog named as the analytics-integrated third option.

The short version

Tool	Pricing model	Self-host / OSS	Best for
Statsig	Flags free, billed on analytics events; Pro $150/mo flat	No (SDKs open source)	Managed experimentation, free flag checks
GrowthBook	$0 self-hosted, or $40/seat/mo cloud	Yes (MIT)	Warehouse-native experimentation, open source
PostHog	Flags free to 1M req/mo, then per request	No (self-host unsupported)	Experiments that read from your analytics

The one-line version - Statsig if you want managed and don’t have a warehouse, GrowthBook if you want open source and do. The rest is the nuance.

Where Statsig wins

Statsig is experiment-first, built by ex-Facebook engineers to recreate Facebook’s internal experimentation stack. The stats engine is the strongest in the broader category - a full statistical engine with sequential testing and CUPED variance reduction. It ingests your events itself, so you don’t need your own data warehouse to get started - a real advantage over GrowthBook for teams without data maturity.

The billing model is the other draw. Flag and config checks are unlimited and free on every tier, because Statsig monetizes analytics and experiment events instead. The free Developer tier gives 2M events, 50,000 session replays and no credit card, and Pro is a flat $150/mo (5M events included, then $0.05 per 1,000) - a predictable number you can budget. Analytics and session replay are built in alongside the experiments. There are 30+ SDKs.

The gotchas. The meter moves on events, so heavy analytics usage is where the bill lives, and Pro is one project per subscription. And the big one - OpenAI acquired Statsig on 2 September 2025 for a reported ~$1.1 billion, with founder Vijaye Raji becoming OpenAI’s CTO of Applications. The product still ships independently, but you’re betting on a roadmap that now sits inside OpenAI. There’s also no genuine self-host - the warehouse-native Enterprise deployment runs compute on your warehouse but isn’t the same as running the application yourself.

Where GrowthBook wins

GrowthBook is the experimentation heavyweight of the open-source flag world. It’s warehouse-native - it queries the data warehouse you already run rather than ingesting a copy of your events, so your analytics data never leaves your infrastructure. The stats engine is the real thing: CUPED, sequential testing, Bayesian analysis, multi-arm bandits and SRM checks, connecting to BigQuery, Snowflake, Databricks and 11 data sources in total. The MIT core self-hosts with unlimited users for $0, Cloud Starter is $0 for up to 3 users, and Cloud Pro is $40 per seat per month - cheaper than most enterprise flag vendors. It’s a Y Combinator company with a reported $22.6M Series A backed by Khosla and Nexus.

The gotcha is dependency and difficulty. GrowthBook needs a properly instrumented data warehouse to deliver its value - no warehouse, far less value, and the Managed Warehouse option adds cost. The statistics also have a genuine learning curve. Reviews consistently flag an engineer-first UI that PMs and marketers need a guided tour for, and documentation that’s comprehensive but hard to navigate. GrowthBook rewards teams with data maturity and punishes teams without it.

Where PostHog fits

If you want experimentation but your center of gravity is product analytics, PostHog is the third option. Its experiments read directly from your product analytics, so the metrics you test against are the same events you already track - and it lands second only to Statsig on experimentation depth. Flags are cheap, with the first 1,000,000 requests a month free.

The gotcha is that PostHog is open source under MIT but self-hosting is officially unsupported, and each product bills separately, so the total can climb across product lines even while flags stay cheap.

Statsig vs GrowthBook - which should you pick?

• You want a managed platform and don’t have a data warehouse - Statsig. It ingests events itself, the free tier is generous, and Pro is a predictable flat price. Price the OpenAI-ownership asterisk in.
• You want open source and your event data to stay in your infrastructure - GrowthBook. Warehouse-native and MIT-licensed, self-hosting unlimited users for $0. This is the data-control pick.
• You already run an instrumented warehouse and have a data-literate person - GrowthBook. That’s exactly the team it rewards, and it’s the best-value serious experimentation platform for them.
• You have no one to own the statistics - lean Statsig. GrowthBook’s CUPED, Bayesian and sequential methods aren’t self-explanatory, and a managed UI lowers the barrier.
• Your experimentation should read from your existing analytics - PostHog, where flags, experiments and analytics share one data model.

The honest bottom line - both are excellent, and the decision is about ownership, not raw capability. Statsig gives you the strongest managed engine with free flag checks and no warehouse requirement, at the cost of proprietary SaaS and an OpenAI-owned roadmap. GrowthBook gives you a genuinely deep open-source, warehouse-native platform that keeps your data yours, at the cost of needing a warehouse and someone who understands the stats. Answer two questions first - do you have an instrumented warehouse, and do you have a data-literate person to drive it? Two yeses point to GrowthBook. A no on either points to Statsig.

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Pricing verified against each vendor’s site on 26 July 2026. The Statsig OpenAI acquisition figure (~$1.1 billion, 2 September 2025) and GrowthBook’s reported $22.6M Series A are from third-party reporting, attributed as such. Full detail on our Statsig, GrowthBook and PostHog reviews.