API Reference

BlockReq supports the standard Ethereum JSON-RPC 2.0 specification. All methods are available through HTTPS and WSS endpoints.

Base URL

HTTPS: https://{chain-slug}.blockreq.com/v1/rpc/public
WSS:   wss://{chain-slug}.blockreq.com/v1/rpc/public

Need higher rate limits? Create a private endpoint to get a dedicated API key.

Request Format

{
  "jsonrpc": "2.0",
  "method": "eth_blockNumber",
  "params": [],
  "id": 1
}

Response Format

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x1234567"
}

Try It Now

# No API key needed — uses the public endpoint
curl -X POST https://eth-mainnet.blockreq.com/v1/rpc/public \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Available Methods

See the detailed method pages:

• EVM JSON-RPC Methods — Full list of supported EVM methods with RU costs

Rate Limiting

Requests are rate-limited based on your plan (e.g., Free: 100 req/s, Growth: 1,500 req/s, Premium: 5,000 req/s). If you exceed the limit, you’ll receive an HTTP 429 response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32005,
    "message": "Rate limit exceeded"
  }
}

Error Codes

HTTP Status	Meaning
401	Missing or invalid API key
402	Insufficient RU balance
429	Rate limit exceeded
502	Upstream node error

WebSocket Subscriptions

Connect via WSS for real-time data:

const ws = new WebSocket("wss://eth-mainnet.blockreq.com/v1/rpc/public");

ws.onopen = () => {
  ws.send(JSON.stringify({
    jsonrpc: "2.0",
    method: "eth_subscribe",
    params: ["newHeads"],
    id: 1
  }));
};

ws.onmessage = (event) => {
  console.log(JSON.parse(event.data));
};