---
title: Configuration
description: To use Flagship in a Cloudflare Worker, add a Flagship binding to your Wrangler configuration file. The binding gives your Worker access to env.FLAGS, which provides methods to evaluate feature flags.
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# Configuration

To use Flagship in a Cloudflare Worker, add a Flagship binding to your Wrangler configuration file. The binding gives your Worker access to `env.FLAGS`, which provides methods to evaluate feature flags.

## Add the binding

Add the `flagship` block to your Wrangler configuration file with a binding name and your app ID.

* [  wrangler.jsonc ](#tab-panel-6849)
* [  wrangler.toml ](#tab-panel-6850)

JSONC

```

{

  "flagship": {

    "binding": "FLAGS",

    "app_id": "<APP_ID>",

  },

}


```

TOML

```

[flagship]

binding = "FLAGS"

app_id = "<APP_ID>"


```

Replace `<APP_ID>` with the app ID from your Flagship app. If you have not created an app yet, refer to the [Get started guide](https://developers.cloudflare.com/flagship/get-started/#create-an-app-and-a-flag). The `binding` field sets the name you use to access Flagship in your Worker code (for example, `env.FLAGS`).

## Bind to multiple apps

A single Worker can bind to multiple Flagship apps. Use the array form to define more than one binding:

* [  wrangler.jsonc ](#tab-panel-6851)
* [  wrangler.toml ](#tab-panel-6852)

JSONC

```

{

  "flagship": [

    {

      "binding": "FLAGS",

      "app_id": "<APP_ID_1>",

    },

    {

      "binding": "EXPERIMENT_FLAGS",

      "app_id": "<APP_ID_2>",

    },

  ],

}


```

Explain Code

TOML

```

[[flagship]]

binding = "FLAGS"

app_id = "<APP_ID_1>"


[[flagship]]

binding = "EXPERIMENT_FLAGS"

app_id = "<APP_ID_2>"


```

Each binding is available as a separate property on the `env` object (for example, `env.FLAGS` and `env.EXPERIMENT_FLAGS`).

## Generate types

After adding the binding, run `npx wrangler types` to generate TypeScript types. This creates the `Env` interface with each binding typed as `Flagship`.

TypeScript

```

interface Env {

  FLAGS: Flagship;

  EXPERIMENT_FLAGS: Flagship;

}


```

## Use the binding

Call evaluation methods on `env.FLAGS` to resolve flag values at runtime. Each method accepts a flag key, a default value, and an optional evaluation context.

* [  JavaScript ](#tab-panel-6853)
* [  TypeScript ](#tab-panel-6854)

JavaScript

```

export default {

  async fetch(request, env) {

    const isEnabled = await env.FLAGS.getBooleanValue("my-feature", false, {

      userId: "user-42",

    });


    return new Response(isEnabled ? "Feature is on" : "Feature is off");

  },

};


```

TypeScript

```

export default {

  async fetch(request: Request, env: Env): Promise<Response> {

    const isEnabled = await env.FLAGS.getBooleanValue("my-feature", false, {

      userId: "user-42",

    });


    return new Response(isEnabled ? "Feature is on" : "Feature is off");

  },

};


```

Refer to the [binding API reference](https://developers.cloudflare.com/flagship/binding/) for the full list of methods.

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/flagship/","name":"Flagship"}},{"@type":"ListItem","position":3,"item":{"@id":"/flagship/configuration/","name":"Configuration"}}]}
```