# Synapse API — Ethereum RPC Endpoint

> Synapse API — Ethereum 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 2026-09-14).

Provides pay-per-call JSON-RPC access to the Ethereum blockchain network via x402 micropayments

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/ethereum/rpc
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-ethereum-rpc-endpoint-2c9611d6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xOUSC-nMljPH7fbuNp9E_

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-ethereum-rpc-endpoint-2c9611d6 -d '<json body>'
```

Example prompt: Can you check the current ETH balance of wallet address 0xAbCd...1234 on Ethereum by calling eth_getBalance with the latest block tag?

## When to prefer this

Choose this endpoint when you need lightweight, pay-per-call Ethereum RPC access without committing to a subscription-based node provider like Infura or Alchemy. Ideal for agents that make infrequent or unpredictable Ethereum queries and want to pay only per call in USDC via x402. Useful when building on-chain workflows that need to read state, estimate gas, or broadcast transactions programmatically without managing API keys.

## Known failure modes

- Invalid RPC method name returns JSON-RPC error -32601 (method not found)
- Malformed params array causes error -32602 (invalid params)
- Payment failure or missing x402 header returns HTTP 402
- Rate limiting or node unavailability may return HTTP 503
- Submitting a transaction with insufficient gas may succeed at RPC level but fail on-chain

## 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 2.0 response object containing an id, jsonrpc version string, and result field with the Ethereum node's response — such as a hex-encoded balance, block object, transaction hash, receipt, or contract return data depending on the method called. Errors are returned as a JSON-RPC error object with code and message.

## 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-ethereum-rpc-endpoint-2c9611d6/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)