RPC WebSocket Support (BETA)

❗️

Compute Unit (CU) values are subject to change as we assess and adjust our pricing to better reflect usage and associated costs.

Blockdaemon's RPC API supports WebSocket connections for real-time blockchain data on supported chains. This guide covers how to connect, which methods are available, and how Compute Units (CUs) are calculated.

Supported Chains

WebSocket Methods & Compute Units

📘

Non-subscription RPC methods over web-socket connection are billed the same as regular RPC methods over HTTP.

• Ethereum
• Polkadot

Ethereum-Compatible Chains

CU Consumption

• Subscribe / Unsubscribe request:
  1 CU per request

• Confirmation responses:
  1 CU

• Event messages (e.g., newHeads):
  10 CU per message

🚧

The minimum charge is 1 CU per action.

💡 Billing Example – Subscribe to eth_subscribe with newHeads

Solana

CU Consumption (Solana)

• Subscribe / Unsubscribe request:
  1 CU per request

• Confirmation responses:
  1 CU

• Event messages (e.g., slotNotification):
  CU varies by event type

🚧

Each subscription type has a specific event type tied to it. For example, you send slotSubscribe → you’ll receive messages of type slotNotification.

💡 Billing Example – Subscribe to accountSubscribe and receive accountNotification

Total Compute Units: 44 CU

Polkadot

• Subscribe / Unsubscribe request: 1 CU per request
• Confirmation responses: 1 CU
• Event messages (e.g., chain_newHead): CU varies by event type

🚧

Each subscription type has a specific event type tied to it. For example, you send state_subscribeStorage → you’ll receive messages of type state_storage.

How to Connect

To connect to the WebSocket endpoint, follow these steps:

1. Authorize your request using one of the following methods:

curl --header "Authorization: Bearer YOUR_API_KEY"

curl --header "X-API-KEY: YOUR_API_KEY"

2. You'll need to install a WebSocket client like wscat, or any other tool you prefer to connect.

npm install -g wscat   //One-time installation

3. Connect to the WebSocket URL with the following URL pattern:

wss://svc.blockdaemon.com/:protocol/:network/native

For example, for Ethereum Mainnet:

wscat --header "Authorization: Bearer YOUR_API_KEY" \
-c wss://svc.blockdaemon.com/ethereum/mainnet/native

4. Once connected, you can send and receive messages using JSON-RPC:

// Subscribe to a WebSocket event (e.g., newHeads)
{"jsonrpc":"2.0","method":"eth_subscribe","params":["newHeads"],"id":1}

// Server responds with a subscription ID
{"jsonrpc":"2.0","id":1,"result":"0xb544f3328760ac404b9e3a4aec6f2ec0"}

// You’ll receive real-time updates as events happen
{"jsonrpc":"2.0","method":"eth_subscription","params":{
  "subscription":"0xb544f3328760ac404b9e3a4aec6f2ec0",
  "result":{ /* event data */ }
}}

// To unsubscribe from the event stream
{"jsonrpc":"2.0","method":"eth_unsubscribe","params":["0xb544f3328760ac404b9e3a4aec6f2ec0"],"id":2}

// Confirmation that you’ve successfully unsubscribed
{"jsonrpc":"2.0","id":2,"result":true}