Environments

Environments let you have different flag values for development, staging, and production.

What Are Environments?

An environment is a separate context where the same flag can have different values. Each environment has its own API key.

Environment	Purpose	Typical Use
Development	Local dev	All flags ON for testing
Staging	QA testing	Test before production
Production	Real users	Careful, gradual rollouts

Example

The same flag can have different states across environments:

Flag: new-checkout-flow

┌─────────────┬─────────┬────────────┐
│ Environment │ Enabled │ Percentage │
├─────────────┼─────────┼────────────┤
│ Development │ ✅ ON   │ 100%       │  ← Always on for devs
│ Staging     │ ✅ ON   │ 100%       │  ← QA is testing it
│ Production  │ ✅ ON   │ 10%        │  ← Slowly rolling out
└─────────────┴─────────┴────────────┘

API Keys

Each environment has its own API key:

Environment	API Key Prefix
Development	`fs_dev_...`
Staging	`fs_staging_...`
Production	`fs_prod_...`

Use the appropriate key for each environment:

const featsync = new Featsync({
  apiKey: process.env.FEATSYNC_DEV_KEY, // fs_dev_...
});

const featsync = new Featsync({
  apiKey: process.env.FEATSYNC_PROD_KEY, // fs_prod_...
});

Creating Environments

Open your project in the dashboard
Click Environments in the header
Click New Environment
Enter a name (e.g., “Staging”)
Copy the new API key

Workflow

A typical workflow using environments:

1. Development

Enable the flag at 100% in Development. Test your feature locally.

FEATSYNC_API_KEY = fs_dev_xxxxx;

2. Staging

Enable in Staging for QA testing. Maybe run some automated tests.

FEATSYNC_API_KEY = fs_staging_xxxxx;

3. Production Rollout

Gradually roll out in Production:

Enable at 10%
Monitor metrics
Increase to 25%, 50%, 100%

FEATSYNC_API_KEY = fs_prod_xxxxx;

Environment Variables

Set the appropriate API key per environment using environment variables:

Next.js

FEATSYNC_API_KEY=fs_dev_xxxxx

FEATSYNC_API_KEY=fs_prod_xxxxx

Docker / CI

services:
  app:
    environment:
      - FEATSYNC_API_KEY=${FEATSYNC_API_KEY}

Platform-Specific

Most hosting platforms (Vercel, Netlify, Heroku) let you set environment variables per deployment environment.

Free Tier

On the Free tier, you have access to:

1 environment (Production)
1 API key

Upgrade to Pro for:

Unlimited environments
Create Development, Staging, or any custom environments

Best Practices

1. Use Different Keys Per Environment

Never use your production key in development:

// Good
const apiKey = process.env.FEATSYNC_API_KEY;

// Bad - hardcoded production key
const apiKey = 'fs_prod_abc123';

2. Enable Flags in Dev First

Test features in Development before enabling in Staging or Production.

3. Use Staging for QA

Before any production rollout, validate in Staging with real-ish data.

4. Roll Out Gradually in Production

Start small (5-10%), monitor, then increase.