growthbook2posthog

Migrate feature flags from GrowthBook to PostHog with an interactive CLI wizard.

Why?

Switching feature flag providers shouldn't mean manually recreating hundreds of flags. growthbook2posthog reads your GrowthBook features, maps them to PostHog's flag format, and creates them in PostHog - handling all the edge cases along the way.

Features

• Interactive TUI - Step-by-step wizard guides you through the entire migration
• Works everywhere - GrowthBook Cloud, PostHog Cloud (US/EU), and self-hosted instances
• Smart key handling - Automatically detects and replaces invalid characters (GrowthBook allows dots, PostHog doesn't) with your choice of separator
• Environment-aware - Optionally append environment names to flag keys for per-environment separation in PostHog
• Safe by default - Preview migration plan before executing, skip existing flags, per-flag error isolation
• Incremental - Re-run migrations safely; existing flags are detected and can be skipped or updated
• Complete mapping - Translates targeting conditions, rollout percentages, force rules, experiments, variants, and payloads

Quick Start

# Install globally
npm install -g growthbook2posthog

# Run the wizard
gb2ph

Or run without installing:

npx growthbook2posthog

How It Works

The wizard walks you through 7 steps:

 Step 1  Configure GrowthBook    Connect to Cloud or self-hosted instance
 Step 2  Configure PostHog       Connect to US/EU Cloud or self-hosted instance
 Step 3  Select Source            Pick GrowthBook project(s) and environment(s)
 Step 4  Select Destination       Pick PostHog project, map environments, choose key format
 Step 5  Preview Migration        Review the plan before making any changes
 Step 6  Execute Migration        Migrate flags with live progress
 Step 7  Summary Report           See results - created, skipped, failed

What Gets Migrated

| GrowthBook | PostHog | Notes | |------------|---------|-------| | Feature key | Flag key | Invalid characters replaced with _ or - | | Description | Flag name | Direct mapping | | Boolean features | Boolean flags | Direct mapping | | String/JSON features | Multivariate flags | Mapped to variants with payloads | | Force rules | Groups (100% rollout) | Conditions translated to property filters | | Rollout rules | Groups (% rollout) | Percentage preserved | | Experiment rules | Multivariate variants | Weights and payloads preserved | | Tags | Tags | Direct mapping | | Archived status | Active: false | Archived flags can be optionally skipped | | Disabled environments | Active: false, 0% rollout | Flag exists but doesn't serve |

Targeting Conditions

MongoDB-style conditions are translated to PostHog property filters:

| GrowthBook | PostHog | |------------|---------| | $eq | exact | | $ne | is_not | | $in / $nin | exact (array) / is_not (array) | | $regex | regex | | $gt / $gte / $lt / $lte | gt / gte / lt / lte | | $exists | is_set / is_not_set | | $and | Single group (AND) | | $or | Multiple groups (OR) |

Environment Strategies

GrowthBook has built-in environments. PostHog does not. The tool supports two approaches:

Option A: Environment-Suffixed Keys

Append the environment name to each flag key. Best for single-project setups (including self-hosted free tier).

my_feature  -->  my_feature_production
my_feature  -->  my_feature_development
my_feature  -->  my_feature_sandbox

Run the migration once per environment. The wizard asks if you want to append environments.

Option B: Separate PostHog Projects

Migrate each environment into a separate PostHog project. Cleanest separation, but requires PostHog Cloud or a paid plan (self-hosted free tier is limited to 1 project).

Key Formatting

PostHog only allows letters, numbers, hyphens (-) and underscores (_) in flag keys.

If your GrowthBook keys use dots or other characters, the wizard detects this and lets you pick a separator:

ais.v1.account.get  -->  ais_v1_account_get   (underscore)
ais.v1.account.get  -->  ais-v1-account-get   (hyphen)

Keys that are already valid pass through unchanged.

Configuration

Connection settings are saved locally after first use. On subsequent runs, the wizard offers to reuse them:

Use saved GrowthBook config? (http://localhost:3100)  Yes
Use saved PostHog config? (https://us.posthog.com)    Yes

Config is stored via conf in your OS config directory.

API Keys

GrowthBook

Go to Settings > API Keys and create a Secret API Key with read access to features, projects, and environments.

PostHog

Go to Settings > Personal API Keys and create a key with scopes:

• Feature Flags: Read + Write
• Projects: Read
• Organizations: Read (+ Write if you want to create projects)

Requirements

• Node.js >= 18
• GrowthBook API access (Secret API Key)
• PostHog API access (Personal API Key)

Known Limitations

• Experiment-ref and safe-rollout rules in GrowthBook have no PostHog equivalent. These are flagged as warnings during migration.
• PostHog's self-hosted free tier is limited to 1 project. Use environment-suffixed keys or upgrade for multi-project support.
• Complex nested MongoDB conditions may need manual review post-migration.

Development

# Clone and install
git clone https://github.com/ashwamegh/growthbook2posthog.git
cd growthbook2posthog
npm install

# Build
npm run build

# Run locally
node dist/bin/gb2ph.js

# Watch mode
npm run dev

License

MIT