> ## Documentation Index
> Fetch the complete documentation index at: https://www.helius.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# slotsUpdatesSubscribe

> Subscribe to receive a notification from the validator on a variety of updates on every slot.

> [!NOTE]
>
> This subscription is unstable. The format of this subscription may change in the future, and may not always be supported.

## Endpoints

Websockets are available on mainnet and devnet with the following URLs:

* **Mainnet** `wss://mainnet.helius-rpc.com/?api-key=<api-key>`
* **Devnet** `wss://devnet.helius-rpc.com/?api-key=<api-key>`

> [!NOTE]
>
> Websockets have a 10-minute inactivity timer; implementing health checks and sending pings every minute is heavily recommended to keep the websocket connection alive.

## Authorizations

**api-key** `string` *required*

Your Helius API key. You can get one for free in the [dashboard](https://dashboard.helius.dev/api-keys).

## Body

**params** `array`

**properties**

**none** `null`

No parameters required.

## Response

**result** `integer`

Subscription id (needed to unsubscribe)

## Notification Format

The notification will be an object with the following fields:

* `err: <string|undefined>` - The error message. Only present if the update is of type "dead".
* `parent: <u64|undefined>` - The parent slot. Only present if the update is of type "createdBank".
* `slot: <u64>` - The newly updated slot
* `stats: <object|undefined>` - Only present if the update is of type "frozen". An object with the following fields:
  * `maxTransactionsPerEntry: <u64>`
  * `numFailedTransactions: <u64>`
  * `numSuccessfulTransactions: <u64>`
  * `numTransactionEntries: <u64>`
* `timestamp: <i64>` - The Unix timestamp of the update in milliseconds
* `type: <string>` - The update type, one of:
  * "firstShredReceived"
  * "completed"
  * "createdBank"
  * "frozen"
  * "dead"
  * "optimisticConfirmation"
  * "root"

```json Request theme={"system"}
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "slotsUpdatesSubscribe"
}
```

```json Response theme={"system"}
{
  "jsonrpc": "2.0",
  "result": 0,
  "id": 1
}
```

```json Notification theme={"system"}
{
  "jsonrpc": "2.0",
  "method": "slotsUpdatesNotification",
  "params": {
    "result": {
      "parent": 75,
      "slot": 76,
      "timestamp": 1625081266243,
      "type": "optimisticConfirmation"
    },
    "subscription": 0
  }
}
```


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