# Synapse API — Soneium Token Balances

> Synapse API — Soneium 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).

Retrieves token balances for a given wallet owner on the Soneium blockchain, optionally filtered by specific contract addresses.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/soneium/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-soneium-token-balances-1d380018
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_dkYhvyPrG-gs4vgU2UqOs

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-soneium-token-balances-1d380018 -d '<json body>'
```

Example prompt: What are all the token balances for the Soneium wallet 0xAbC123...? Also check specifically for the tokens at contract addresses 0xToken1... and 0xToken2....

## When to prefer this

Use this endpoint when you specifically need token balance data on the Soneium blockchain. It supports filtering by contract address, making it ideal for targeted token lookups rather than full portfolio scans. Prefer this over generic EVM balance endpoints when the user's wallet or protocol is on Soneium specifically.

## Known failure modes

- Invalid or malformed owner address returns an error or empty result
- Non-existent contract addresses in the filter list may return zero balances or be omitted
- Wallet with no token holdings returns an empty balances array
- Network downtime or Soneium RPC issues may cause timeouts or 5xx errors
- Payment failure (insufficient USDC or x402 error) prevents call from completing

## 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 wallet on the Soneium network. Each entry typically includes the token contract address and the corresponding balance amount. Optionally filtered to only the specified contract addresses if provided.

## 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-soneium-token-balances-1d380018/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)