/vercel-flags

name: vercel-flags
description: "Feature flags, A/B tests, and gradual rollouts with Vercel Flags, in any app or framework. Use whenever the user is planning, adding, or changing a feature flag, toggle, kill switch, experiment, percentage rollout, or targeting rule, or wants to gate or hide a feature for some users, even before a library or provider is chosen. Covers choosing an integration (Flags SDK, `@vercel/flags-core`, OpenFeature), the Vercel dashboard, the `vercel flags` CLI (create, inspect, set, split, rollout, rules, segments, evaluations, archive), OIDC vs SDK keys, `FLAGS_SECRET`, and Flags Explorer overrides. For `flag()` declarations, adapters, precompute, and the Flags Explorer endpoint in Next.js or SvelteKit code, load the `flags-sdk` skill."
summary: "Vercel Flags guidance — plan a flag, choose Flags SDK vs @vercel/flags-core vs OpenFeature, manage flags with the vercel flags CLI, run rollouts and A/B tests, and retire flags safely."
metadata:
  priority: 6
  docs:
    - "https://vercel.com/docs/flags"
    - "https://vercel.com/docs/cli/flags"
  sitemap: "https://vercel.com/sitemap.xml"
  importPatterns:
    - '@vercel/flags-core'
  bashPatterns:
    - '\bvercel\s+flags\b'
    - '\bvc\s+flags\b'
    - '\bnpm\s+(install|i|add)\s+[^\n]*@vercel/flags-core\b'
    - '\bpnpm\s+(install|i|add)\s+[^\n]*@vercel/flags-core\b'
    - '\bbun\s+(install|i|add)\s+[^\n]*@vercel/flags-core\b'
    - '\byarn\s+add\s+[^\n]*@vercel/flags-core\b'
  promptSignals:
    phrases:
      - "feature flag"
      - "feature flags"
      - "vercel flags"
      - "feature gate"
      - "feature gating"
      - "a/b test"
      - "a/b testing"
      - "ab test"
      - "ab testing"
      - "flag rollout"
      - "gradual rollout"
      - "percentage rollout"
      - "kill switch"
      - "flag variant"
      - "traffic split"
      - "targeting rules"
      - "flag rules"
      - "flag segments"
      - "flag targeting"
      - "flag evaluations"
      - "flag overrides"
      - "existing flag"
      - "archive flag"
      - "flags-core"
    allOf:
      - [flag, rollout]
      - [flag, variant]
      - [flag, toggle]
      - [flag, experiment]
      - [flag, archive]
      - [experiment, variant]
      - [split, test]
    anyOf:
      - "flag"
      - "experiment"
      - "experimentation"
      - "rollout"
      - "variant"
    noneOf:
      - "command-line flag"
      - "command line flag"
      - "cli flag"
      - "compiler flag"
      - "flag emoji"
      - "rolling release"
    minScore: 6
retrieval:
  aliases:
    - feature flags
    - feature toggles
    - vercel flags
    - a/b testing
    - flags core
  intents:
    - add a feature flag
    - run an a/b test
    - gate a feature
    - roll out gradually
    - manage flags from cli
    - archive a feature flag
  entities:
    - Vercel Flags
    - vercel flags CLI
    - "@vercel/flags-core"
    - OpenFeature
    - FLAGS_SECRET
    - SDK keys

Vercel Flags

Vercel Flags is Vercel's feature flags platform. Flags are created and managed in the Vercel dashboard or with the `vercel flags` CLI, evaluated server-side in your app, and switched per environment (Development, Preview, Production) without a redeploy.

• Docs: https://vercel.com/docs/flags
• CLI reference: https://vercel.com/docs/cli/flags

Use this skill to decide how a feature should be flagged, to create and change flags, and to run rollouts and experiments. Write app code with the skill that matches the stack (see [Choose an approach](#choose-an-approach)). Do not leave CLI steps as "next steps" for the user; execute them yourself.

Route the request

• **Planning** ("put this behind a flag", "roll this out to 10%", "A/B test the pricing page", "add a kill switch"): follow [Plan a flag](#plan-a-flag), then [Choose an approach](#choose-an-approach).
• **Create or manage a flag with no code change** (create, inspect, enable, set, split, rollout, rules, archive): follow [Manage flags with the CLI](#manage-flags-with-the-cli). This needs an authenticated CLI, not SDK packages, Toolbar, Flags Explorer, or `.env.local` (except `vercel flags override`, which reads `FLAGS_SECRET`).
• **Add a flag to an app that already uses the Flags SDK** (`flags` in `package.json`): load the `flags-sdk` skill right away; it creates the flag on Vercel and declares it in code.
• **Implement in code otherwise**: follow [Choose an approach](#choose-an-approach) and load the matching skill or reference. Inside an app repository, treat an ambiguous request as plan, create, and implement.

Choose an approach

Check the project before writing code.

• **Already using another flag provider** (Statsig, LaunchDarkly, PostHog, GrowthBook, and so on): keep it. On Next.js or SvelteKit, the Flags SDK connects to it through an adapter; load the `flags-sdk` skill. On any other stack, use the provider's own SDK. Rollouts, targeting, and experiments for that provider are configured in its own dashboard, not with `vercel flags`; the CLI and lifecycle sections of this skill do not apply.
• **No provider yet**: use Vercel Flags. Pick the integration by stack ([SDKs](https://vercel.com/docs/flags/vercel-flags/sdks)):
• **Next.js or SvelteKit**: the Flags SDK (`flags` + `@flags-sdk/vercel`). It adds Flags Explorer integration and precompute for static pages. Load the `flags-sdk` skill. If it is not available, suggest `npx skills add vercel/flags@flags-sdk` (do not auto-install).
• **Any other framework or a plain server** (for example Express): `@vercel/flags-core`. See [Other frameworks](#other-frameworks).
• **The user wants provider portability or already uses OpenFeature**: the Vercel Flags OpenFeature provider ([Using OpenFeature with Vercel Flags](https://vercel.com/docs/flags/vercel-flags/sdks/openfeature)).

The dashboard and the `vercel flags` CLI work the same for every integration.

Plan a flag

Decide these before creating the flag; the kind cannot be changed later.

• **Kind**: `boolean` for on/