Next.js (Pages Router) quickstart

1. Install hypertune

Once you have a Next.js application (using the Pages Router) ready, install Hypertune's JavaScript SDK:

npm

npm install hypertune

yarn

pnpm

2. Set environment variables

Define the following environment variables in your .env file:

.env

NEXT_PUBLIC_HYPERTUNE_TOKEN=token
HYPERTUNE_FRAMEWORK=nextPages
HYPERTUNE_OUTPUT_DIRECTORY_PATH=generated

Replace token with your main project token which you can find in the Settings tab of your project.

3. Generate the client

Generate a type-safe client to access your flags by running:

npm

npx hypertune

yarn

pnpm

4. Use the client

Add a new file called getHypertune.ts that exports a getHypertune function:

lib/getHypertune.ts

import { createSourceForServerOnly } from '@/generated/hypertune'

const hypertuneSource = createSourceForServerOnly({
  token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
})

export default async function getHypertune({
  isApiRoute = false,
}: {
  isApiRoute?: boolean
} = {}) {
  await hypertuneSource.initIfNeeded()

  hypertuneSource.setRemoteLoggingMode(
    isApiRoute ? 'normal' : 'off'
  )

  return hypertuneSource.root({
    args: {
      context: {
        environment: process.env.NODE_ENV,
        user: {
          id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
          name: 'Example User',
          email: '[email protected]',
        },
      },
    },
  })
}

Components

To use flags in components, first create a new <AppHypertuneProvider> component that wraps the generated <HypertuneProvider> component:

components/AppHypertuneProvider.tsx

import { HypertuneProvider } from '@/generated/hypertune.react'

export default function AppHypertuneProvider({
  children,
}: {
  children: React.ReactNode
}) {
  return (
    <HypertuneProvider
      createSourceOptions={{
        token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
      }}
      rootArgs={{
        context: {
          environment: process.env.NODE_ENV,
          user: {
            id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
            name: 'Example User',
            email: '[email protected]',
          },
        },
      }}
    >
      {children}
    </HypertuneProvider>
  )
}

Wrap your app with the <AppHypertuneProvider> component in _app.tsx:

pages/_app.tsx

import type { AppProps } from 'next/app'
import AppHypertuneProvider from '@/components/AppHypertuneProvider'
import '@/styles/globals.css'

export default function App({ Component, pageProps }: AppProps) {
  return (
    <AppHypertuneProvider>
      <Component {...pageProps} />
    </AppHypertuneProvider>
  )
}

Then use the generated useHypertune hook:

components/ExampleComponent.tsx

import { useHypertune } from '@/generated/hypertune.react'

export default function ExampleComponent() {
  const hypertune = useHypertune()

  const exampleFlag = hypertune.exampleFlag({ fallback: false })

  return <div>Example Flag: {String(exampleFlag)}</div>
}

If you access a flag immediately after the app loads, you'll get your hardcoded fallback value if the SDK hasn't initialized from Hypertune Edge yet. This can result in layout shift or a flicker if the flag value changes when the SDK initializes.

To avoid this, wrap your page with the generated <HypertuneHydrator> and <HypertuneRootProvider> components, passing them dehydratedState and rootArgs from the server:

pages/index.tsx

import {
  GetServerSideProps,
  InferGetServerSidePropsType,
} from 'next'
import ExampleComponent from '@/components/ExampleComponent'
import { DehydratedState, RootArgs } from '@/generated/hypertune'
import {
  HypertuneHydrator,
  HypertuneRootProvider,
} from '@/generated/hypertune.react'
import getHypertune from '@/lib/getHypertune'

type Props = {
  dehydratedState: DehydratedState | null
  rootArgs: RootArgs
}

export const getServerSideProps = (async () => {
  const hypertune = await getHypertune()

  const dehydratedState = hypertune.dehydrate()
  const rootArgs = hypertune.getRootArgs()

  return { props: { dehydratedState, rootArgs } }
}) satisfies GetServerSideProps<Props>

export default function Page({
  dehydratedState,
  rootArgs,
}: InferGetServerSidePropsType<typeof getServerSideProps>) {
  return (
    <HypertuneHydrator dehydratedState={dehydratedState}>
      <HypertuneRootProvider rootArgs={rootArgs}>
        <ExampleComponent />
      </HypertuneRootProvider>
    </HypertuneHydrator>
  )
}

Notes

• Dynamic rendering: Using getServerSideProps makes your entire page dynamic. To use flags and run experiments on static pages (e.g. marketing pages), see the guide on using Hypertune on static pages.

• Content Security Policy: If you have a CSP, add the following to your connect-src directive: https://edge.hypertune.com https://gcp.fasthorse.workers.dev. This enables reporting of flag evaluations, experiment exposures, and analytics events.

getServerSideProps

API Routes

Middleware

5. (Optional) Add the Hypertune Toolbar

The Hypertune Toolbar lets you view and override feature flags directly in your frontend. Follow the guide to add it to your app.

6. (Optional) Include a build-time snapshot

To improve reliability, you can include a snapshot of your flag logic in the generated client at build time. The SDK will instantly initialize from the snapshot first before fetching the latest flag logic from Hypertune Edge.

Add the following environment variable to your .env file:

HYPERTUNE_INCLUDE_INIT_DATA=true

Then regenerate the client.

You can keep the snapshot fresh by setting up a webhook to regenerate the client on every Hypertune commit. In this case, you don't need to initialize from Hypertune Edge at all, eliminating network latency and bandwidth, improving both performance and efficiency.

7. (Optional) Use Vercel Edge Config

If your Next.js app is deployed on Vercel, you can use Edge Config to initialize the Hypertune SDK on the server with near-zero latency.

1. Install the integration

1. Go to the Hypertune page in the Vercel Integrations marketplace and click "Add Integration".

2. Select your Vercel team and project.

3. Continue and log into Hypertune.

4. Connect your Hypertune project to a new or existing Edge Config store. Copy the displayed environment variables for later. They contain your Hypertune Token, Edge Config Connection String and Edge Config Item Key.

5. Go to your Vercel dashboard and select the project you want to use the Hypertune integration with. Go to Settings > Environment Variables and add the following:

   1. NEXT_PUBLIC_HYPERTUNE_TOKEN, set to your Hypertune Token

   2. EDGE_CONFIG, set to your Edge Config Connection String

   3. EDGE_CONFIG_HYPERTUNE_ITEM_KEY, set to your Edge Config Item Key

2. Use the integration

Pull the environment variables to your .env.development.local file by running:

vercel env pull .env.development.local

Install the @vercel/edge-config package:

npm

npm install @vercel/edge-config

yarn

pnpm

Finally, update your getHypertune function to create an Edge Config client and pass it along with your Edge Config Item Key when creating the Hypertune source:

lib/getHypertune.ts

import { createClient } from '@vercel/edge-config'
import { VercelEdgeConfigInitDataProvider } from 'hypertune'
import { createSourceForServerOnly } from '@/generated/hypertune'

const hypertuneSource = createSourceForServerOnly({
  token: process.env.NEXT_PUBLIC_HYPERTUNE_TOKEN!,
  initDataProvider:
    process.env.EDGE_CONFIG &&
    process.env.EDGE_CONFIG_HYPERTUNE_ITEM_KEY
      ? new VercelEdgeConfigInitDataProvider({
          edgeConfigClient: createClient(
            process.env.EDGE_CONFIG
          ),
          itemKey: process.env.EDGE_CONFIG_HYPERTUNE_ITEM_KEY,
        })
      : undefined,
})

export default async function getHypertune({
  isApiRoute = false,
}: {
  isApiRoute?: boolean
} = {}) {
  await hypertuneSource.initIfNeeded()

  hypertuneSource.setRemoteLoggingMode(
    isApiRoute ? 'normal' : 'off'
  )

  return hypertuneSource.root({
    args: {
      context: {
        environment: process.env.NODE_ENV,
        user: {
          id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
          name: 'Example User',
          email: '[email protected]',
        },
      },
    },
  })
}

Next steps

Now you can update the logic for exampleFlag from the Hypertune UI without updating your code or waiting for a new build, deployment, or app release.

To add a new flag, create it in the Hypertune UI then regenerate the client.