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Feature Flag a Checkout Flow in 5 Minutes

Learn how to wrap a new checkout experience behind a feature flag and roll it out safely.

Prerequisites​

  • FeatureSignals server running (locally or hosted)
  • An API key for your environment
  • Node.js SDK installed (npm install @featuresignals/node-sdk)

Step 1: Create the Flag​

In the FeatureSignals dashboard, navigate to your project and create a new flag:

  • Key: new-checkout
  • Name: New Checkout Flow
  • Type: Boolean
  • Default value: false

Or use the API:

curl -X POST https://api.featuresignals.com/v1/projects/{projectID}/flags \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "key": "new-checkout",
    "name": "New Checkout Flow",
    "type": "boolean",
    "defaultValue": false
  }'

Step 2: Install and Initialize the SDK​

npm install @featuresignals/node-sdk

Initialize the client in your application entry point:

const { FeatureSignals } = require('@featuresignals/node-sdk');

const client = new FeatureSignals({
  apiKey: process.env.FEATURESIGNALS_API_KEY,
});

await client.initialize();

Step 3: Wrap Your Checkout Code​

Use boolVariation to branch between the old and new checkout paths:

app.post('/checkout', async (req, res) => {
  const user = req.user;

  const useNewCheckout = await client.boolVariation('new-checkout', {
    userID: user.id,
    email: user.email,
    plan: user.plan,
  }, false);

  if (useNewCheckout) {
    return handleNewCheckout(req, res);
  }

  return handleLegacyCheckout(req, res);
});

The third argument (false) is the fallback value returned if the flag can't be evaluated.

Step 4: Enable in Staging First​

  1. Go to the Environments tab for the new-checkout flag
  2. Select your Staging environment
  3. Toggle Enabled to true
  4. Click Save

Run your test suite against staging to verify the new checkout works correctly.

Step 5: Roll Out to Production​

Once verified in staging, enable the flag in production:

  1. Select Production environment
  2. Set percentage to 10% for a canary release
  3. Monitor error rates and conversion metrics
  4. Gradually increase to 50%, then 100%

Or use the promote API to copy staging state to production:

curl -X POST https://api.featuresignals.com/v1/projects/{projectID}/flags/new-checkout/promote \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "fromEnvID": "staging-env-id",
    "toEnvID": "production-env-id"
  }'

Step 6: Clean Up​

Once the new checkout is stable and serving 100% of traffic:

  1. Remove the flag check from your code — keep only the new checkout path
  2. Deploy the simplified code
  3. Delete the flag from the dashboard
// After cleanup — no more flag check
app.post('/checkout', async (req, res) => {
  return handleNewCheckout(req, res);
});

Next Steps​