Feature Flags

Vercel provides many paths, options, and configurations to work with feature flags in your application. Feature flags are a powerful tool that allows you to control the visibility of features in your application, enabling you to ship, test, and experiment with confidence.

Vercel provides a way for you to work with Flags in a way that suits your team's workflow and at any step in the lifecycle. You can choose to adopt as much or as little of the following steps as you need. The options can be used independently of each other and combined with each other as needed for the specific project.

1. You can choose to either implement flags in code, using the Flags SDK in Next.js App Router or SvelteKit, or use an SDK from your existing feature flag provider. To learn more, see Implementing Feature Flags.
2. You can choose to manage feature flags, regardless of how they're implemented, through the Vercel Toolbar to view, override, and share your application's feature flags. To learn more, see Managing Feature Flags from the Toobar.
3. You can integrate feature flags with Vercel's observability features. To learn more, see Observing your flags.
4. You can use an Edge Config integration to speed up how your application loads feature flags. To learn more, see Optimizing your feature flags.

If you're using Next.js App Router, or Sveltekit for your application, you have the option of implementing feature flags as code. This allows you to manage feature flags in your application codebase, including the ability in Next.js to use feature flags for static pages by generating multiple variants and routing between them using middleware.

• Vercel is compatible with any feature flag provider including LaunchDarkly, Optimizely, Statsig, Hypertune, Split, and custom feature flag setups.
• Flags SDK: Architectural design patterns for working with feature flags.
• Using Flags SDK in Next.js: Learn how to use the @vercel/flags/next submodule to use feature flags in Next.js App Router.
• Using Flags SDK in SvelteKit: Learn how to set up and use the @vercel/flags/sveltekit submodule for SvelteKit.

Using the Vercel Toolbar, you're able to view, override, and share feature flags for your application without leaving your browser tab.

You can manage feature flags from the toolbar in any development environment that your team has enabled the toolbar for. This includes local development, preview deployments, and production deployments.

• Using Feature Flags in the Vercel Toolbar: Learn how to view and override your application's feature flags from the Vercel Toolbar.
• Implementing Feature Flags in the Vercel Toolbar: Learn how to set up the Vercel Toolbar so you can see and override your application's feature flags.

Feature flags play a crucial role in the software development lifecycle, enabling safe feature rollouts, experimentation, and A/B testing. When you integrate your feature flags with the Vercel platform, you can improve your application by using Vercel's observability features.

• Integrate Feature Flags with Runtime Logs: Learn how to send feature flag data to Vercel logs.
• Integrate Feature Flags with Web Analytics: Learn how to tag your page views and custom events with feature flags.

An Edge Config is a global data store that enables experimentation with feature flags, A/B testing, critical redirects, and IP blocking. It enables you to read data at the edge without querying an external database or hitting upstream servers. With Vercel Integrations, you can connect with external providers to synchronize their flags into your Edge Config.

With Vercel's optimizations, you can read Edge Config data at negligible latency. The vast majority of your reads will complete within 15ms at P99, or as low as 0ms in some scenarios.

• Vercel Edge Config: Experiment with A/B testing by storing feature flags in your Edge Config.
• Vercel Edge Config Quickstart: Get started with reading data from Edge Config.