---
title: KV bindings
description: KV bindings connect a Cloudflare Worker to a KV namespace for reading and writing data.
image: https://developers.cloudflare.com/dev-products-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/kv/llms.txt  
> Use this file to discover all available pages before exploring further. 

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# KV bindings

KV [bindings](https://developers.cloudflare.com/workers/runtime-apis/bindings/) allow for communication between a Worker and a KV namespace.

Configure KV bindings in the [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/).

## Access KV from Workers

A [KV namespace](https://developers.cloudflare.com/kv/concepts/kv-namespaces/) is a key-value database replicated to Cloudflare's global network.

To connect to a KV namespace from within a Worker, you must define a binding that points to the namespace's ID.

The name of your binding does not need to match the KV namespace's name. Instead, the binding should be a valid JavaScript identifier, because the identifier will exist as a global variable within your Worker.

A KV namespace will have a name you choose (for example, `My tasks`), and an assigned ID (for example, `06779da6940b431db6e566b4846d64db`).

To execute your Worker, define the binding.

In the following example, the binding is called `TODO`. In the `kv_namespaces` portion of your Wrangler configuration file, add:

* [  wrangler.jsonc ](#tab-panel-9338)
* [  wrangler.toml ](#tab-panel-9339)

JSONC

```
{  "$schema": "./node_modules/wrangler/config-schema.json",  "name": "worker",  // ...  "kv_namespaces": [    {      "binding": "TODO",      "id": "06779da6940b431db6e566b4846d64db"    }  ]}
```

TOML

```
"$schema" = "./node_modules/wrangler/config-schema.json"name = "worker"
[[kv_namespaces]]binding = "TODO"id = "06779da6940b431db6e566b4846d64db"
```

With this, the deployed Worker will have a `TODO` field in their environment object (the second parameter of the `fetch()` request handler). Any methods on the `TODO` binding will map to the KV namespace with an ID of `06779da6940b431db6e566b4846d64db` – which you called `My Tasks` earlier.

JavaScript

```
export default {  async fetch(request, env, ctx) {    // Get the value for the "to-do:123" key    // NOTE: Relies on the `TODO` KV binding that maps to the "My Tasks" namespace.    let value = await env.TODO.get("to-do:123");
    // Return the value, as is, for the Response    return new Response(value);  },};
```

## Use KV bindings when developing locally

When you use Wrangler to develop locally with the `wrangler dev` command, Wrangler will default to using a local version of KV to avoid interfering with any of your live production data in KV. This means that reading keys that you have not written locally will return `null`.

To have `wrangler dev` connect to your Workers KV namespace running on Cloudflare's global network, set `"remote" : true` in the KV binding configuration. Refer to the [remote bindings documentation](https://developers.cloudflare.com/workers/local-development/#remote-bindings) for more information.

* [  wrangler.jsonc ](#tab-panel-9340)
* [  wrangler.toml ](#tab-panel-9341)

JSONC

```
{  "$schema": "./node_modules/wrangler/config-schema.json",  "name": "worker",  // ...  "kv_namespaces": [    {      "binding": "TODO",      "id": "06779da6940b431db6e566b4846d64db"    }  ]}
```

TOML

```
"$schema" = "./node_modules/wrangler/config-schema.json"name = "worker"
[[kv_namespaces]]binding = "TODO"id = "06779da6940b431db6e566b4846d64db"
```

## Access KV from Durable Objects and Workers using ES modules format

[Durable Objects](https://developers.cloudflare.com/durable-objects/) use ES modules format. Instead of a global variable, bindings are available as properties of the `env` parameter [passed to the constructor](https://developers.cloudflare.com/durable-objects/get-started/#2-write-a-durable-object-class).

An example might look like:

JavaScript

```
import { DurableObject } from "cloudflare:workers";
export class MyDurableObject extends DurableObject {  constructor(ctx, env) {    super(ctx, env);  }
  async fetch(request) {    const valueFromKV = await this.env.NAMESPACE.get("someKey");    return new Response(valueFromKV);  }}
```

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