# Synapse API — Plasma Token Balances

> Synapse API — Plasma 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 2026-09-13).

Fetches ERC-20/token balances for a given wallet owner address across specified contract addresses on blockchain networks

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/plasma/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-plasma-token-balances-053f37e2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_p4FUwlEBVOPRnDiNWk3Ga

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-plasma-token-balances-053f37e2 -d '<json body>'
```

Example prompt: Check the token balances for wallet 0xAbC123... and these contract addresses: 0xToken1, 0xToken2 — I want to know how much of each token that wallet holds.

## When to prefer this

Use this endpoint when you need to quickly look up on-chain token balances for one or more ERC-20 token contracts for a specific wallet address, especially when paying per-call via x402 micropayments without needing a persistent API key subscription.

## Known failure modes

- Invalid or malformed owner address returns an error
- Unknown or invalid contract address may return zero balance or error
- Network/RPC errors for specific chains may cause lookup failure
- Missing required owner field returns validation error
- Empty contractAddresses array may return empty results

## 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 the specified owner address across each provided contract address, including the balance amounts held by that wallet for each token contract queried.

## 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-plasma-token-balances-053f37e2/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)