KV Storage

Overview

Workers KV is a global, low-latency key-value data store. It supports exceptionally high read volumes with low latency, making it ideal for storing configuration data, cached content, and user preferences.

Managing Namespaces

Create a Namespace

Create a new KV namespace with an optional preview namespace for development:

wrangler kv namespace create <namespace> [--preview]

Options:

<namespace> - The name of the new namespace
--preview - Create a preview namespace for testing
--env <environment> - Target a specific environment
--update-config - Automatically add the namespace to your wrangler.json
--name <binding-name> - Custom binding name for the namespace

Example:

# Create a production namespace
wrangler kv namespace create my-cache

# Create a preview namespace
wrangler kv namespace create my-cache --preview

After creation, add the namespace to your configuration:

wrangler.json

{
  "kv_namespaces": [
    {
      "binding": "MY_CACHE",
      "id": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
    }
  ]
}

List Namespaces

View all KV namespaces in your account:

wrangler kv namespace list

Outputs JSON with namespace details including IDs and titles.

Rename a Namespace

Rename an existing KV namespace:

wrangler kv namespace rename <old-name> --new-name <new-name>

Options:

<old-name> - Current namespace name (positional)
--namespace-id <id> - Target by ID instead of name
--new-name <name> - New namespace name (required)

Example:

wrangler kv namespace rename old-cache --new-name new-cache

Delete a Namespace

Delete a namespace and all its data:

wrangler kv namespace delete <namespace>

Options:

<namespace> - Namespace name to delete
--binding <name> - Target by binding name
--namespace-id <id> - Target by namespace ID
--preview - Delete a preview namespace
-y, --skip-confirmation - Skip the confirmation prompt

This action is irreversible and permanently deletes all data in the namespace.

Key-Value Operations

Put
Get
List
Delete

Write a Key-Value Pair

Store a value in a KV namespace:

wrangler kv key put <key> <value> --binding <binding>

Options:

<key> - The key to write to
<value> - The value to write (mutually exclusive with --path)
--path <file> - Read value from a file
--binding <name> - Binding name from your config
--namespace-id <id> - Namespace ID to use
--preview - Write to preview namespace
--ttl <seconds> - Time-to-live in seconds
--expiration <timestamp> - UNIX timestamp for expiration
--metadata <json> - Arbitrary JSON metadata
--local - Use local storage (for dev)
--persist-to <dir> - Directory for local persistence

Examples:

# Write a simple value
wrangler kv key put "config:theme" "dark" --binding MY_CACHE

# Write from a file
wrangler kv key put "html:home" --path ./index.html --binding MY_CACHE

# Write with expiration (24 hours)
wrangler kv key put "session:abc" "user-data" --binding MY_CACHE --ttl 86400

# Write with metadata
wrangler kv key put "user:123" "data" --binding MY_CACHE --metadata '{"version":"1.0"}'

Read a Key-Value Pair

Retrieve a value from a KV namespace:

wrangler kv key get <key> --binding <binding>

Options:

<key> - The key to read
--binding <name> - Binding name from your config
--namespace-id <id> - Namespace ID to use
--preview - Read from preview namespace (defaults to false)
--text - Decode value as UTF-8 text
--local - Use local storage
--persist-to <dir> - Directory for local persistence

Examples:

# Get a value as text
wrangler kv key get "config:theme" --binding MY_CACHE --text

# Get binary data (outputs to stdout)
wrangler kv key get "image:logo" --binding MY_CACHE > logo.png

# Get from local namespace
wrangler kv key get "test:key" --binding MY_CACHE --local

List All Keys

List all keys in a namespace:

wrangler kv key list --binding <binding>

Options:

--binding <name> - Binding name from your config
--namespace-id <id> - Namespace ID to use
--prefix <prefix> - Filter keys by prefix
--preview - List keys in preview namespace
--local - Use local storage
--persist-to <dir> - Directory for local persistence

Examples:

# List all keys
wrangler kv key list --binding MY_CACHE

# List keys with a prefix
wrangler kv key list --binding MY_CACHE --prefix "user:"

Output format:

[
  {
    "name": "config:theme",
    "expiration": null,
    "metadata": null
  },
  {
    "name": "user:123",
    "expiration": 1234567890,
    "metadata": {"version": "1.0"}
  }
]

Delete a Key-Value Pair

Remove a key from a namespace:

wrangler kv key delete <key> --binding <binding>

Options:

<key> - The key to delete
--binding <name> - Binding name from your config
--namespace-id <id> - Namespace ID to use
--preview - Delete from preview namespace
--local - Use local storage
--persist-to <dir> - Directory for local persistence

Example:

wrangler kv key delete "session:expired" --binding MY_CACHE

Bulk Operations

Bulk Put

Upload multiple key-value pairs from a JSON file:

wrangler kv bulk put <filename> --binding <binding>

JSON Format:

[
  {
    "key": "config:theme",
    "value": "dark",
    "expiration_ttl": 86400,
    "metadata": {"version": "2.0"}
  },
  {
    "key": "config:lang",
    "value": "en",
    "base64": false
  }
]

Fields:

key - Key name (required)
value - Value to store (required)
expiration - UNIX timestamp for expiration
expiration_ttl - Seconds until expiration
metadata - JSON object for metadata
base64 - Whether value is base64 encoded

Bulk Get

Retrieve multiple values by keys (Open Beta):

wrangler kv bulk get <filename> --binding <binding>

Input Format:

["key1", "key2", "key3"]

Or with objects:

[{"name": "key1"}, {"name": "key2"}]

Bulk Delete

Delete multiple keys from a namespace:

wrangler kv bulk delete <filename> --binding <binding>

Options:

-f, --force - Skip confirmation prompt

Input Format:

["key1", "key2", "key3"]

Local Development

Using Local Storage

Test KV operations locally without affecting production data:

# Write to local storage
wrangler kv key put "test" "value" --binding MY_CACHE --local

# Read from local storage
wrangler kv key get "test" --binding MY_CACHE --local

# Specify persistence directory
wrangler kv key put "test" "value" --binding MY_CACHE --local --persist-to ./.wrangler

Local mode stores data in .wrangler/state/v3/kv/ by default.

Worker Integration

Access KV from your Worker code:

export default {
  async fetch(request, env) {
    // Get a value
    const theme = await env.MY_CACHE.get("config:theme");
    
    // Get with metadata
    const { value, metadata } = await env.MY_CACHE.getWithMetadata("user:123");
    
    // Put a value
    await env.MY_CACHE.put("session:abc", "data", {
      expirationTtl: 3600,
      metadata: { userId: "123" }
    });
    
    // Delete a value
    await env.MY_CACHE.delete("session:old");
    
    // List keys
    const { keys } = await env.MY_CACHE.list({ prefix: "user:" });
    
    return new Response("OK");
  }
};

Best Practices

Key Naming

Use prefixes for organization: user:123, config:theme
Keep keys under 512 bytes
Use consistent naming conventions
Avoid special characters when possible

Value Limits

Maximum value size: 25 MiB
Maximum metadata size: 1 KiB
Use expiration for temporary data
Consider compression for large values

Performance

KV is optimized for high read volumes
Writes propagate globally (eventual consistency)
Use list() pagination for large datasets
Cache frequently accessed data

Development

Use preview namespaces for testing
Test with --local flag during development
Use --persist-to for consistent local state
Version your data with metadata

Error Handling

Common errors and solutions:

Namespace not found

Ensure the namespace exists and you’re using the correct binding name or namespace ID:

wrangler kv namespace list

Key not found

The specified key doesn’t exist in the namespace. Check the key name and use kv key list to verify.

Invalid metadata JSON

Metadata must be valid JSON. Use proper escaping:

--metadata '{"version":"1.0","author":"user"}'

Value too large

Values must be under 25 MiB. Consider:

Compressing the data
Splitting into multiple keys
Using R2 for larger objects

R2 Storage - Object storage for large files
D1 Database - Serverless SQL database
Durable Objects - Stateful coordination

Get Started

Core Tools

Development

Deployment

Platform Features

Advanced

Overview

Managing Namespaces

Create a Namespace

List Namespaces

Rename a Namespace

Delete a Namespace

Key-Value Operations

Write a Key-Value Pair

Read a Key-Value Pair

List All Keys

Delete a Key-Value Pair

Bulk Operations

Bulk Put

Bulk Get

Bulk Delete

Local Development

Using Local Storage

Worker Integration

Best Practices

Key Naming

Value Limits

Performance

Development

Error Handling

Build docs developers (and LLMs) love

Get Started

Core Tools

Development

Deployment

Platform Features

Advanced

​Overview

​Managing Namespaces

​Create a Namespace

​List Namespaces

​Rename a Namespace

​Delete a Namespace

​Key-Value Operations

​Write a Key-Value Pair

​Read a Key-Value Pair

​List All Keys

​Delete a Key-Value Pair

​Bulk Operations

Bulk Put

Bulk Get

Bulk Delete

​Local Development

​Using Local Storage

​Worker Integration

​Best Practices

Key Naming

Value Limits

Performance

Development

​Error Handling

​Related Commands

Build docs developers (and LLMs) love

Overview

Managing Namespaces

Create a Namespace

List Namespaces

Rename a Namespace

Delete a Namespace

Key-Value Operations

Write a Key-Value Pair

Read a Key-Value Pair

List All Keys

Delete a Key-Value Pair

Bulk Operations

Local Development

Using Local Storage

Worker Integration

Best Practices

Error Handling

Related Commands