One local fast path, five EVM networks

Use standard JSON-RPC, simulate a transaction before your bot signs it, and receive confirmed contract logs without polling every block.

Five isolated networks

Ethereum, Base, Arbitrum, Optimism, and Polygon have separate routes, WebSockets, cache keys, and persisted local state.

Read and simulate

Preview return data, gas, and access lists. Transaction submission remains disabled by default.

Signed callbacks

Pro log webhooks use stable event IDs and HMAC signatures so your receiver can authenticate and deduplicate retries.

HTTP routes

Ethereum  /api/v1/rpc
Base      /api/v1/base/rpc
Arbitrum  /api/v1/arbitrum/rpc
Optimism  /api/v1/optimism/rpc
Polygon   /api/v1/polygon/rpc

Install the SDK

npm install @rpc-relay/sdk

import { createRpcRelayClient } from '@rpc-relay/sdk';

const relay = createRpcRelayClient(); // http://127.0.0.1:8545
const block = await relay.request({ method: 'eth_blockNumber', params: [] });
const preview = await relay.simulateTransaction({ from, to, data, value: '0x0' });

Simulate without submitting

curl http://127.0.0.1:8545 \
  -H 'content-type: application/json' \
  --data '{"jsonrpc":"2.0","id":1,"method":"rpc_relay_simulateTransaction","params":[{"from":"0x...","to":"0x...","data":"0x..."},"latest"]}'

The response includes success, returnData, gasEstimate, an access list when supported, and per-step errors. It always reports submitted: false.

Create a confirmed-log webhook

curl https://rpc-cache-worker.rpc-relay-cache.workers.dev/api/webhooks \
  -H "Authorization: Bearer $PRO_TOKEN" \
  -H 'content-type: application/json' \
  --data '{"chain":"base","callback_url":"https://bot.example/webhook","address":"0x...","topics":["0x..."]}'

Store the returned signing secret once. Deliveries include X-RPC-Relay-Event-Id and X-RPC-Relay-Signature: sha256=.... Compute HMAC-SHA256 over the exact raw request body, compare signatures in constant time, and deduplicate by event ID before processing.

Pilot limits: three subscriptions per Pro account, confirmed logs only, at-least-once delivery, up to 50 logs per callback batch. Pending and dropped-transaction events require a separate mempool feed and are not advertised as available.

Trace methods

Pro forwards debug_traceCall, debug_traceTransaction, trace_call, and trace_transaction. Availability and response shape depend on the selected upstream; unsupported methods return an explicit JSON-RPC error.

Security boundary

Warm hits remain on the device. Miss padding reduces simple request correlation but does not make upstream traffic invisible. RPC Relay never asks the SDK or MCP server for wallet keys, and simulation does not authorize a transaction.