---
title: Configuration
description: Add and configure a Flagship binding in your Wrangler configuration file to evaluate feature flags in a Worker.
image: https://edgetunnel-b2h.pages.dev/dev-products-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://edgetunnel-b2h.pages.dev/flagship/llms.txt  
> Use this file to discover all available pages before exploring further. 

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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-9276)
* [  wrangler.toml ](#tab-panel-9277)

**JSONC**

```jsonc
{
  "flagship": [
    {
      "binding": "FLAGS",
      "app_id": "<APP_ID>",
    },
  ],
}
```

**TOML**

```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://edgetunnel-b2h.pages.dev/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-9278)
* [  wrangler.toml ](#tab-panel-9279)

**JSONC**

```jsonc
{
  "flagship": [
    {
      "binding": "FLAGS",
      "app_id": "<APP_ID_1>",
    },
    {
      "binding": "EXPERIMENT_FLAGS",
      "app_id": "<APP_ID_2>",
    },
  ],
}
```

**TOML**

```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**

```ts
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-9280)
* [  TypeScript ](#tab-panel-9281)

**JavaScript**

```js
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**

```ts
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://edgetunnel-b2h.pages.dev/flagship/binding/) for the full list of methods.

## Local development

Flagship bindings work with `wrangler dev`. Local Workers use the live Flagship app configured by `app_id`. There is no local flag store. Make sure your local Wrangler configuration points to a valid Flagship app before testing evaluations.

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```