The feature flags toolkit
Flags SDK is a free, open-source library for using feature flags in Next.js and SvelteKit.
Try the Flags SDK
Set persistent flags for this pageKeep it dithered
Toggle between headline options for A/B testing
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Using flags as code
The SDK sits between your application and the source of your flags, helping you follow best practices and keep your website fast.
Works with any provider
Use any flag provider, or none at all. Flexible integrations for your projects.
Effortless integration
Integrate with App Router, Pages Router, and Routing Middleware.
Release strategically
Ideal for A/B testing and controlled rollouts. Experiment with confidence.
Effortless setup
With a simple declarative API to define and use your feature flags.
flags.ts
import { flag } from 'flags/next';export const exampleFlag = flag({ key: 'example-flag', decide() { return Math.random() > 0.5; },});app/page.tsx
import { exampleFlag } from "../flags";export default async function Page() { const example = await exampleFlag(); return <div>Flag {example ? "on" : "off"}</div>;}
