- description
- Toggle features instantly without deploying code. A/B test variants, gradual rollouts from 1% to 100%, and emergency kill switches for AI agents.
- keywords
- feature flag, feature toggle, A/B testing, gradual rollout, canary release, kill switch, percentage rollout, remote config
- name
- feature-flag-manager
- triggers
- toggle feature, enable feature, disable feature, A/B test, rollout percentage, kill switch, feature flag
feature-flag-manager
Deploy features safely. Toggle on/off instantly, run A/B tests, and roll out gradually from 1% to 100% — no code redeployment needed.
What It Does
Control feature visibility in real-time without pushing new code:
- Instant toggle — Enable/disable features with one command
- Gradual rollout — Start with 1% of users, increase slowly
- A/B testing — Test variants against each other with automatic traffic splitting
- Kill switch — Emergency off button for buggy features
- User targeting — Show features to specific users or groups
Quick Start
# 1. Create a feature flag
node flag.js create dark-mode --description "Dark theme UI"
# 2. Enable for 10% of users
node flag.js update dark-mode --percentage 10
# 3. Check if enabled for current user
node flag.js enabled dark-mode --user-id alice
# → true (or false based on percentage)
# 4. Gradually increase to 100%
node flag.js update dark-mode --percentage 50
node flag.js update dark-mode --percentage 100Common Use Cases
🚀 Safe Feature Releases
# Instead of: deploy → pray → rollback
# Do this: deploy (disabled) → enable 5% → monitor → 25% → 100%
node flag.js create new-checkout-flow
node flag.js update new-checkout-flow --percentage 5
# Monitor error rates...
node flag.js update new-checkout-flow --percentage 100🧪 A/B Test Pricing Pages
# Test 3 variants: 50% see current, 25% see v1, 25% see v2
node flag.js create pricing-test --variants control,v1,v2 --weights 50,25,25
# In your code, get variant for each user
node flag.js variant pricing-test --user-id user123
# → "v1"🚨 Emergency Kill Switch
# New feature causing errors? Disable instantly without redeploying
node flag.js toggle broken-feature --off
# Fixed? Re-enable
node flag.js toggle broken-feature --onAll Commands
| Command | Purpose |
|---|---|
create <name> | Create a new flag |
toggle <name> | Enable/disable instantly |
update <name> --percentage N | Set rollout percentage (0-100) |
enabled <name> | Check if enabled for user |
variant <name> | Get A/B variant for user |
list | Show all flags and status |
history <name> | See change history |
export | Export config for backup |
Configuration
Flags stored in .featureflags/config.json:
{
"flags": {
"dark-mode": {
"enabled": true,
"percentage": 25,
"description": "Dark theme support"
},
"pricing-test": {
"enabled": true,
"percentage": 100,
"variants": ["control", "v1", "v2"],
"weights": [50, 25, 25]
}
}
}Integration Example
const flag = require('./flag.js');
async function renderDashboard(userId) {
// Check if new dashboard is enabled for this user
if (await flag.enabled('new-dashboard', { userId })) {
return renderNewDashboard();
}
return renderLegacyDashboard();
}