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Statsig refers to feature flags as feature gates across the console and SDKs. The terms are interchangeable throughout this guide.
Once your Statsig account is ready, follow the steps below to create and test-drive a new feature gate.
1

Create a feature gate

Navigate to the Feature Gates page and click Get Started (or Create if you already have gates).
Feature Gates page with Create button
Give the gate a clear name and description—for example, Mobile Registration with a note about the new mobile sign-up flow.
2

Target mobile platforms

New gates default to returning false until you add targeting. Click Add New Rule, choose Operating System → Any of, and select Android and iOS. Set the pass percentage to 100% and click Add Rule, then Save.
Adding a mobile targeting rule
3

Add an internal testing rule

Layer on a second rule for your team—for example Email → Contains any of with your company domain—so employees can exercise the feature regardless of device.
Gate with mobile and email rules
4

Generate a client API key

Head to Project Settings → API Keys and copy the Client API key. Keep server secret keys on backends only, and use console API keys for programmatic configuration work.
5

Load the JavaScript SDK

Statsig supports many platforms—see Client SDK options for alternatives. This walkthrough uses the browser SDK so you can experiment directly in DevTools.
Paste the snippet below into the browser console on any site to fetch the SDK from jsDelivr:
const script = document.createElement('script');
script.src = 'https://cdn.jsdelivr.net/npm/@statsig/js-client@3/build/statsig-js-client+session-replay+web-analytics.min.js';
document.head.appendChild(script);
Injecting the SDK via DevTools
6

Initialize and check the gate

Replace YOUR_SDK_KEY with the client key from Step 4 and run:
const client = new window.Statsig.StatsigClient('YOUR_SDK_KEY', {});
await client.initializeAsync();
Then call:
client.checkGate('mobile_registration');
You should see false because the current session is not mobile and doesn’t use the employee email domain.
7

Simulate a mobile environment

Enable the mobile device toolbar in Chrome DevTools.
Chrome DevTools mobile device toolbar icon
Re-evaluate the user to pick up the new environment and re-check the gate:
await client.updateUserAsync({});
client.checkGate('mobile_registration');
The gate should now return true for the mobile profile.
Gate returning true for mobile rule
8

Test the employee backdoor

Switch DevTools back to the desktop view and update the user with a company email:
await client.updateUserAsync({ email: '[email protected]' });
client.checkGate('mobile_registration');
The gate passes again thanks to the email rule.
Gate returning true via email rule
9

Flush exposures and inspect diagnostics

client.flush();
Open the gate’s Diagnostics tab to confirm each exposure, including the failing desktop check, mobile pass, and employee pass.
Diagnostics exposure stream showing recent checks

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Use the gate in production

Wrap feature logic in a gate check so only targeted users see the experience: 
if (client.checkGate('mobile_registration')) {
  show(mobileRegistrationPage);
} else {
  show(oldRegistrationPage);
}
Happy feature gating!