---
title: puter.kv.set()
description: Save or update values in key-value store.
platforms: [websites, apps, nodejs, workers]
---
When passed a key and a value, will add it to the user's key-value store, or update that key's value if it already exists.
Each app has its own private key-value store within each user's account. Apps cannot access the key-value stores of other apps - only their own.
## Syntax
```js
puter.kv.set(key, value)
puter.kv.set(key, value, expireAt)
```
## Parameters
#### `key` (String) (required)
A string containing the name of the key you want to create/update. The maximum allowed `key` size is **1 KB**.
#### `value` (String | Number | Boolean | Object | Array)
A string containing the value you want to give the key you are creating/updating. The maximum allowed `value` size is **400 KB**.
#### `expireAt` (Number) (optional)
A number containing when the key should expire in timestamp seconds.
## Return value
A `Promise` that will resolves to `true` when the key-value pair has been created or the existing key's value has been updated.
## Examples
Create a new key-value pair
```html;kv-set
```