# 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 2026-10-12).

Fetches token balances for a given wallet address across multiple ERC-20 or similar contract addresses on supported blockchain networks.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/stable/token/balances?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-token-balances-lookup-36ff112a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_X97aBCJUzliOvUSm8ZOBN

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-36ff112a -d '<json body>'
```

Example prompt: Check the token balances for wallet address 0xAbC123...def and these contract addresses: 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 and 0xdAC17F958D2ee523a2206206994597C13D831ec7.

## When to prefer this

Use this endpoint when you need to quickly look up token balances for a specific wallet across one or more ERC-20 or similar token contracts without setting up your own blockchain node. It is ideal for pay-per-call use cases where you don't want a subscription, need multi-contract batch queries in a single call, and require coverage across a wide range of 57+ blockchain networks.

## Known failure modes

- Invalid or malformed wallet address returns an error or empty result
- Non-existent or incorrect contract addresses return zero balances or errors
- Unsupported blockchain network not included in the 57+ supported chains may return an error
- Rate limiting or payment failure if x402 micropayment is not properly handled
- Network congestion or RPC unavailability on the target chain may cause timeout

## 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 for the specified owner wallet, one entry per contract address provided, including token amounts 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-token-balances-lookup-36ff112a/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)