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Get started

Section titled “Get started”

Flags come with the SDK you already have: feature flags in Bridge Express ride on the same bridge instance you create for auth, so there’s no separate flags module to install and no flag-specific init call. Once a route is authenticated, adding a flag requirement is one option on bridge.protect(...).

1. Set up the SDK

Section titled “1. Set up the SDK”

createBridge(...) takes your appId (all a flags-capable backend needs) and returns the instance whose middleware factories evaluate flags for you:

import express from 'express';
import { createBridge } from '@nebulr-group/bridge-express';

const bridge = createBridge({
  appId: process.env.BRIDGE_APP_ID!,
  guard: {
    defaultAccess: 'protected',
    rules: [{ path: '/health', privilege: 'ANONYMOUS' }],
  },
});

const app = express();
app.use(bridge.auth()); // authenticate every route registered below

The flag evaluator is wired up internally when you call createBridge(...); there is no flag-specific setup call. Configuration comes from the same appId (and optional apiBaseUrl) you already pass; flags evaluate over the derived {apiBaseUrl}/cloud-views endpoint. See Configuration for the full BridgeConfig reference.

2. Create a flag in Control Center

Section titled “2. Create a flag in Control Center”

In Control Center (your admin dashboard at app.thebridge.dev), open Feature Flags and create a boolean flag, for example beta-access, and leave it off.

3. Gate your first route

Section titled “3. Gate your first route”

A flag is evaluated against the requesting user’s access token, so the route must be authenticated (the caller sends a user JWT). Add featureFlag to bridge.protect(...):

import { Router } from 'express';
const router = Router();

router.get('/beta/feature', bridge.protect({ featureFlag: 'beta-access' }), (req, res) => {
  res.json({ feature: 'beta-data', user: req.bridgeUser });
});

export default router;

While the flag is off for a caller, the middleware returns 403 Forbidden before your handler runs:

{
  "statusCode": 403,
  "error": "Forbidden",
  "message": "Feature flag 'beta-access' is not enabled"
}

Tip: Flag gating applies to the user-JWT path only; it is not evaluated for API-token callers. Use it to gate what a signed-in person can reach.

4. Flip it and watch the route open

Section titled “4. Flip it and watch the route open”

Go back to Control Center and turn beta-access on. The route opens for the users your rule targets, no redeploy: the change governs the next evaluation (a caller inside the per-token cache window may briefly see the previous answer). Flip it off again and the route closes the same way.

That’s the whole loop: create a flag, gate a route with a safe default of “closed”, and control it from Control Center from then on.

Next steps

Section titled “Next steps”