# Synapse API — Token Balances Lookup

> Synapse API — Token Balances Lookup 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 2026-09-13).

Retrieves token balances for a given wallet owner address across specified ERC-20 or multi-chain contract addresses

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/tempo/token/balances
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-token-balances-lookup-2a0cc9a4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_YMvDEjJsxFnWKWIR9zLDl

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-token-balances-lookup-2a0cc9a4 -d '<json body>'
```

Example prompt: Can you check the token balances for wallet address 0xAbC123...def and include the USDC contract at 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48?

## When to prefer this

Choose this endpoint when you need to fetch on-chain token balances for a specific wallet address across one or more ERC-20 or compatible token contracts in a pay-per-call model without managing your own RPC infrastructure. Ideal for spot checks, portfolio snapshots, or pre-transaction balance validation where real-time data is needed cheaply.

## Known failure modes

- Invalid or malformed wallet address returns an error or empty result
- Unknown or unsupported contract address returns zero balance or error
- Network congestion may cause delayed responses
- Missing required 'owner' field causes a validation error
- Unsupported blockchain network for a given contract address may yield no data

## 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 list of token balances associated with the specified owner address and contract addresses, including balance amounts per token contract, enabling portfolio analysis and pre-transaction verification.

## 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-token-balances-lookup-2a0cc9a4/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)