Vercel Flags

12 posts · Mar 2023 – Jun 2026

What this trail covers

Vercel's platform continues to enhance its feature flagging capabilities by integrating them deeper into the developer workflow. This includes the general availability of the Flags Explorer within the Vercel Toolbar for direct management and overriding of flags, new first-party integrations with experimentation providers like Statsig via the Vercel Marketplace, and updates to the open-source Flags SDK with a new adapter architecture for easier integration with various providers. The Flags SDK enables server-side experimentation and integrates with Web Analytics and Runtime Logs for deeper insights and debugging. A new experimental Next.js design pattern allows for precomputing flags in Middleware to avoid jank and improve performance.

All Vercel trails

Jun 2026Vercel Flags: Platform-native feature flagsThis post details the server-side evaluation of feature flags in Vercel, highlighting its integration with Next.js React Server Components for seamless rendering without client-side requests. It introduces the 'precompute' pattern for static pages, enabling all variants to be built and distributed via CDN, with Routing Middleware directing users to the correct one. The post also emphasizes automatic flag registration from code and agent-native management via the `vercel flags` CLI.
May 2025Introducing the Flags Explorer, first-party integrations, and updates to the Flags SDKThis post introduces the general availability of the Flags Explorer in the Vercel Toolbar, allowing direct management and session-specific overrides of feature flags. It also announces the new Experimentation category on the Vercel Marketplace, featuring integrations like Statsig, which offers low-latency flag evaluation by syncing flags into Vercel's Edge Config. Updates to the open-source Flags SDK include a new adapter architecture for connecting to multiple providers, exemplified by the `@flags-sdk/statsig` package that enables managing Statsig flags within the Vercel Flags Explorer.
Jul 2024Flags as Code in Next.jsIntroduces the new Flags SDK for Next.js and SvelteKit, enabling server-side evaluation of feature flags. Details guiding principles: flags as functions, server-side evaluation only, and flags accepting no arguments on the call side. Explains primitive flags and progressions with tradeoffs: hardcoded flags (slow to change, affects everyone) vs. overriding from Vercel Toolbar (session-specific overrides for testing). Discusses using environment variables and Edge Config as flag sources, and mentions OpenFeature integration. Highlights the benefit of precomputing feature flags for static page variants.
May 2024Introducing deeper integrations for feature flags in VercelThis post introduces deeper integrations for feature flags within Vercel's Developer Experience Platform. Key contributions include: 1. Overriding flags directly from the Vercel Toolbar, storing overrides in an encrypted cookie. 2. Integration with Vercel Web Analytics to filter and break down page views and custom events by feature flags. 3. Integration with Vercel Runtime Logs to provide context for debugging and troubleshooting. 4. Introduction of the `@vercel/flags/next` package for a new experimental Next.js design pattern that enables server-side experimentation by precomputing flags in Middleware, aiming to eliminate jank and improve performance.
Mar 2024Introducing feature flag management from the Vercel ToolbarIntroduces the ability to manage and override feature flags directly from the Vercel Toolbar. This integration allows developers to stay in their workflow by overriding flags from any provider (LaunchDarkly, Optimizely, Statsig, Split, Hypertune, etc.) via API Routes and script tags. The implementation involves rendering flag values via a script tag and communicating metadata through an API route. Overrides are respected by reading the `vercel-flag-overrides` cookie. This enhances QA and testing by enabling per-session overrides in local, preview, and production environments.
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Jun 2023Vercel Edge Config + LaunchDarkly: Low latency, global feature flags to your favorite frontend frameworkIntroduces an integration with LaunchDarkly to sync feature flags into Vercel Edge Config. Provides a new `@launchdarkly/vercel-server-sdk` package to bootstrap a LaunchDarkly client from Edge Config data, enabling low-latency flag lookups. Demonstrates a code example for consuming flags in an Edge Function.
Apr 2023A/B Testing and Feature Flags with sub-millisecond performanceIntroduces Vercel Edge Config, a globally distributed, ultra-low latency data store for configuration data, optimized for fast reads and infrequent writes. This enables dynamic data storage alongside functions, with data replicated to all Vercel regions for instant availability. It allows for near-zero latency experimentation (0ms to 10ms lookups) and dynamic changes without new deployments. Integrates with experimentation tools like LaunchDarkly, Statsig, and Split. Also details dynamic routing with Edge Middleware using Edge Config for blocking IPs/user-agents and advanced security rules.
Mar 2023How to build zero-CLS A/B tests with Next.js and Vercel Edge ConfigThis post details the implementation of a high-performance A/B testing engine for vercel.com using Next.js and Vercel Edge Config. It introduces a system for creating type-safe experiments, pre-rendering experiment variations using dynamic routes and `getStaticPaths`/`getStaticProps`, serving experiments to users via Next.js Middleware rewrites powered by Edge Config and user cookies, and automatically capturing events with a React Context. The engine aims to provide zero Cumulative Layout Shift (CLS) and a great developer experience for experiments.