What is GrowthBook?

GrowthBook is an open-source feature-flagging and experimentation platform built around three core pillars.

The three pillars

1. Feature Flagging

Control feature visibility without requiring a new deploy. Wrap any code path behind a flag, then toggle it on or off — per environment, per audience segment, or for a percentage rollout — straight from the GrowthBook UI.

2. A/B Testing / Experimentation

Run controlled experiments to measure the real impact of your changes. GrowthBook assigns users to variants, tracks exposures via your SDK, and then queries your data warehouse to compute statistical results — including Bayesian and frequentist analyses.

3. Analytics on your own data warehouse

GrowthBook connects directly to your warehouse — Snowflake, BigQuery, Redshift, ClickHouse, and more. It queries your existing event tables and computes metrics on the fly. Your raw event data never leaves your infrastructure.

Self-host vs GrowthBook Cloud

	Self-Host	GrowthBook Cloud
Cost	Free	Free tier, then paid
Data control	Full	Managed
Setup	Docker Compose	Sign up
URL	`localhost:3000`	`app.growthbook.io`

Key concepts

Concept	Definition
Feature	A named flag in GrowthBook that maps to a value in your code.
Environment	A deployment context — `dev`, `staging`, or `production`. Each feature can have different rules per environment.
SDK Connection	The pair of `apiHost` + `clientKey` that identifies your app to GrowthBook’s CDN.
Experiment	A controlled A/B or multivariate test linked to one or more Features.
Metric	A measurable outcome (conversion, revenue, latency) defined against your warehouse tables.

Reading a JSON flag

GrowthBook supports more than booleans. Use getFeatureValue to read a JSON flag with a typed fallback:

import { GrowthBook } from '@growthbook/growthbook';

const gb = new GrowthBook({
  apiHost: 'https://cdn.growthbook.io',
  clientKey: 'sdk-YOUR_DEV_KEY',
});

await gb.init({ timeout: 2000 });

// JSON flag — returns the object or the fallback
const config = gb.getFeatureValue('checkout-config', { maxItems: 10, theme: 'light' });
console.log(config.theme); // 'dark' if the flag is on, 'light' otherwise

import { GrowthBook } from '@growthbook/growthbook';

const gb = new GrowthBook({
  apiHost: 'https://cdn.growthbook.io',
  clientKey: 'sdk-YOUR_DEV_KEY',
});

await gb.init({ timeout: 2000 });

// JSON flag — returns the object or the fallback
const config = gb.getFeatureValue('checkout-config', { maxItems: 10, theme: 'light' });
console.log(config.theme); // 'dark' if the flag is on, 'light' otherwise