Progressive Delivery and Feature Flags: Ship Faster with Less Risk

Deploying code and releasing features are two different things. Progressive delivery separates them. You deploy code to production behind a feature flag, then gradually release it to users while monitoring for problems.

The Core Concept

Traditional deployment: Code goes live → all users see it → hope nothing breaks.

Progressive delivery: Code goes live (hidden) → enable for 1% of users → monitor → expand to 10% → monitor → expand to 50% → full release.

If anything goes wrong at any stage, flip the flag off. No rollback needed.

Feature Flag Platforms (2026)

Practical Use Cases

Percentage Rollouts

Release a new checkout flow to 5% of users. Compare conversion rates against the old flow. Expand or revert based on data.

Beta Programs

Give power users early access to features. Collect feedback before general release. Build advocacy.

Kill Switches

Disable resource-intensive features during traffic spikes. Turn off third-party integrations if an API is down.

A/B Testing

Feature flags naturally enable A/B testing. Show variant A to half your users and variant B to the other half.

Environment-Based

Enable debug tools in staging, disable in production. Show admin features only for internal users.

Implementation Pattern

// Simple feature flag check
const flags = await getFeatureFlags(userId);

if (flags.newCheckout) {
  return <NewCheckoutFlow />;
}
return <LegacyCheckoutFlow />;

// Progressive rollout with percentage
const flag = await getFlag('new-checkout', {
  userId,
  percentage: 10, // 10% of users
  attributes: {
    plan: user.plan,
    country: user.country,
  }
});

Risks to Manage

1. Flag debt: Old flags accumulate and become technical debt. Set expiration dates
2. Testing complexity: Each flag doubles your test matrix. Be disciplined
3. Performance overhead: Too many flag evaluations add latency. Use edge evaluation
4. Consistency: Users should see the same flag state across sessions
5. Dependency chains: Flags that depend on other flags create complexity

Best Practices

• Remove flags within 2 weeks of full rollout
• Use naming conventions: release-*, experiment-*, ops-*
• Log all flag changes for audit trails
• Test both flag states in CI/CD
• Start with simple boolean flags, add complexity only when needed

Our Approach

We use feature flags in every major project. The ability to ship confidently, test in production, and roll back instantly is worth the modest overhead. For most small business sites, Vercel Edge Config or PostHog provides everything needed without additional infrastructure.