# Synapse API — Optimism Token Balances

> Synapse API — Optimism Token Balances 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 2026-09-15).

Fetches ERC-20 token balances for a given wallet address on the Optimism (OP Mainnet) blockchain, optionally filtered by contract addresses.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/optimism/token/balances
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-optimism-token-balances-348a16d6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-uNcTvxrAnUmGs4SU8O_6

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-token-balances-348a16d6 -d '<json body>'
```

Example prompt: What are the ERC-20 token balances for wallet 0xAbC...123 on Optimism? Also check specifically for USDC (0x7F5c764cBc14f9669B88837ca1490cCa17c31607) and OP (0x4200000000000000000000000000000000000042).

## When to prefer this

Use this endpoint when you specifically need ERC-20 token balances on the Optimism (OP Mainnet) L2 network. Prefer this over generic on-chain tools if you want a pay-per-call, no-subscription model via x402 micropayments and are querying the Optimism chain specifically rather than Ethereum mainnet or other L2s.

## Known failure modes

- Invalid or malformed wallet address returns an error
- Non-existent contract address returns zero balance or an error
- Network/RPC issues may cause timeouts
- Payment failure (x402) prevents the call from completing
- Empty contractAddresses array may return all tokens or nothing depending on implementation

## 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 token balance data for each specified ERC-20 contract (or all tokens held) for the given wallet on Optimism, including token quantities and likely token metadata such as symbol and decimals.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "owner": {
   "type": "string"
  },
  "contractAddresses": {
   "type": "array",
   "items": {
    "type": "string"
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synapse-api-optimism-token-balances-348a16d6/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)