Feature Flags in 5 Minutes with Node.js

Feature flags let you deploy code without releasing it. You push to production, but new features stay hidden behind a flag until you flip the switch. No more long-lived feature branches, no more "release day" anxiety.

In this tutorial, you'll add feature flags to a Node.js app using ToggleTown's Node SDK. The whole thing takes about 5 minutes.

1. Create a ToggleTown account

Sign up at app.toggletown.com — it's free for up to 5 flags, no credit card required. Create a project, and you'll get an environment API key (starts with env_).

2. Install the SDK

npm install @toggletown/sdk-node

3. Initialize the client

The SDK fetches your flag configuration on startup and evaluates flags locally — no network call per check, zero latency.

import { ToggleTownNode } from '@toggletown/sdk-node';

const client = new ToggleTownNode({
  apiKey: process.env.TOGGLETOWN_API_KEY, // env_xxx
});

await client.initialize();
console.log('ToggleTown ready —', client.flagCount(), 'flags loaded');

The SDK polls for updates every 30 seconds by default, so flag changes propagate without restarting your app.

4. Wrap your feature

Use getBooleanFlag to check whether a feature should be enabled. Pass the flag key, a default value, and an optional user context for targeting.

app.get('/dashboard', (req, res) => {
  const showNewDashboard = client.getBooleanFlag(
    'new-dashboard',
    false, // default if flag doesn't exist
    { userId: req.user.id, email: req.user.email }
  );

  if (showNewDashboard) {
    return res.render('dashboard-v2');
  }

  return res.render('dashboard');
});

The user context enables targeting rules — roll out to specific users, emails matching a pattern, or a percentage of traffic.

5. Create the flag in ToggleTown

Head to the ToggleTown dashboard, create a boolean flag called new-dashboard, and toggle it on. Your app picks up the change within 30 seconds.

Want to be more careful? Use percentage rollout to enable the flag for 10% of users first, then ramp up to 50%, then 100%. If something breaks, flip the flag off instantly — no deployment needed.

Beyond booleans

ToggleTown supports four flag types. Use the right one for your use case:

// Boolean — on/off toggles
const enabled = client.getBooleanFlag('new-feature', false);

// String — variant selection, themes, copy testing
const theme = client.getStringFlag('app-theme', 'light');

// Number — limits, thresholds, tuning
const maxRetries = client.getNumberFlag('max-retries', 3);

// JSON — complex configuration
const config = client.getJsonFlag('onboarding-flow', {
  steps: ['welcome', 'setup'],
});

Recap

1. Sign up and get your environment API key
2. npm install @toggletown/sdk-node
3. Initialize the client with your API key
4. Wrap features with getBooleanFlag (or other flag types)
5. Create and toggle flags in the dashboard

Next steps

• Read the full SDK docs for targeting rules, segments, and experiments
• Check out the feature flag best practices guide
• We also have SDKs for JavaScript, React, Python, and Go

---

ToggleTown is a simple, open feature flag platform for modern teams. Free tier available, no credit card required.