# Synapse API — Optimism RPC Endpoint

> Synapse API — Optimism RPC Endpoint is a paid API for AI agents from synapse-api-brown.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-13).

Proxies JSON-RPC calls to the Optimism (OP Mainnet) blockchain network, enabling agents to read chain state, send transactions, and interact with smart contracts.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/optimism/rpc?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-optimism-rpc-endpoint-374b9df9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_6o1TbegAgPFXiokOl3kBW

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability synapse-api-optimism-rpc-endpoint-374b9df9 -d '<json body>'
```

Example prompt: Check the ETH balance of address 0xAbC...123 on Optimism mainnet using eth_getBalance with the latest block tag.

## When to prefer this

Choose this endpoint when you need pay-per-call access to Optimism (OP Mainnet) RPC without managing node infrastructure or long-term subscriptions. Ideal for agents that make occasional or unpredictable RPC calls and want to pay micro-amounts per call via x402/USDC rather than committing to a monthly node provider plan. Prefer this over raw Infura/Alchemy when your agent already operates in a crypto-native, x402-payment context.

## Known failure modes

- Invalid or unsupported RPC method name returns JSON-RPC error -32601
- Malformed params array causes parse or invalid params error -32700/-32602
- Payment not attached or insufficient USDC triggers 402 Payment Required before RPC call is made
- Network congestion or node downtime returns timeout or -32603 internal error
- Querying a block or tx hash that doesn't exist returns null result

## How this service works

High-speed API suite for AI processing, web scraping, and smart data utilities across 57+ blockchain networks. Pay-per-call via x402.

## Output

Returns a standard JSON-RPC response object containing the result field with chain data (balance, block, receipt, logs, etc.) or an error object with code and message if the call fails. Output format mirrors the Ethereum JSON-RPC spec applied to Optimism's OP Mainnet.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "method": {
   "type": "string"
  },
  "params": {
   "type": "array",
   "items": {}
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synapse-api-optimism-rpc-endpoint-374b9df9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from synapse-api-brown.vercel.app](https://www.zero.xyz/host/synapse-api-brown.vercel.app/llms.txt)