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GrowthBook

Open-source feature flags + A/B testing. Loved by engineering teams.

4.7/5 Free + paid · free plan A/B Testing & CRO
Visit website → Try free
Best for Developer-first SaaS, open-source fans
Pricing Free + paid
Setup time Under 30 min
Learning curve Moderate
Support Email, chat, CRO consultants on enterprise
Company GrowthBook
Launched 2020

About GrowthBook

GrowthBook is an A/B Testing & CRO tool that developer-first SaaS and open-source fans rely on day-to-day. On the strengths side, open-source + self-hostable; on the depth side, uses your existing data (no new tracking). The things you'll actually touch most days are Feature flags and A/B testing. There's a free plan to explore before paying, with paid upgrades when you need them. The best open-source A/B testing tool for developer-first SaaS.

Available on

Web appSDKsAPISelf-hosted

Integrates with

SnowflakeBigQueryPostgreSQLMixpanelAmplitudeGA4Slack

Who it's for

A quick filter before you spend time on GrowthBook — read both sides before committing.

Use it if…

  • Developer-first SaaS teams
  • Companies with existing data warehouses
  • Teams wanting open-source control

Skip it if…

  • Non-technical teams
  • Teams needing visual editor
  • Pure marketing-led CRO

Pros and cons

Pros

  • Open-source + self-hostable
  • Uses your existing data (no new tracking)
  • Server-side feature flags included
  • Hits the core a/b testing & cro workflow without forcing a hunt for second tools
  • Pricing lands in the right band for its target buyer

Cons

  • Requires engineering to deploy
  • No visual editor for marketers
  • Smaller community vs. Statsig
  • Not the cheapest option in the category — the free alternatives cover basics
  • Advanced features sit behind higher-tier plans most small teams won't need

Features

The capabilities you actually get when you sign up for GrowthBook.

  1. 01

    Feature flags

    Server-side flag rollouts with telemetry

  2. 02

    A/B testing

    Statistical analysis on warehouse data

  3. 03

    Open-source

    Self-host for free

  4. 04

    Core workspace

    The main editor or dashboard where day-to-day a/b testing & cro work happens

  5. 05

    Integrations hub

    Connects to the tools your stack already uses so data doesn't live in silos

  6. 06

    Reporting and dashboards

    Built-in reports and exportable dashboards for stakeholder reviews

Pricing

A free plan to start, then paid tiers for the full set of features.

Open Source

Free

  • Unlimited
  • Self-hosted

Cloud Pro

$20/user /mo

  • Managed
  • SSO
  • Advanced features

Frequently asked questions

What people usually want to know before signing up for GrowthBook.

Can I really self-host GrowthBook for free?

Yes — Docker install, full feature set.

Do I need my own data warehouse?

Yes — GrowthBook queries your existing data.

Does the editor cause page flicker or hurt Core Web Vitals?

Modern async-rendering engines keep flicker under 100ms. Older synchronous snippets can add 300ms+ to LCP — test before you ship.

How much traffic do I need to run a test?

Roughly 1,000 conversions per variant per week for a 10% MDE at 95% confidence. Below that, tests take longer than the lifetime of the feature.

Is server-side testing worth the extra work?

For logged-in features and pricing changes, yes — it's the only way to test without exposing your experiment architecture to the client.

Bottom line

Should you use GrowthBook?

The best open-source A/B testing tool for developer-first SaaS. For marketing-led CRO, VWO or Optimizely is friendlier.

Visit website → Try free