# SYNTHORA ERC-20 Token Balance Lookup

> SYNTHORA ERC-20 Token Balance Lookup is a paid API for AI agents from rpc-erc20-balance.hergertsynthora.com, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).

Fetches the ERC-20 token balance of a given wallet address on a specified chain using the standard balanceOf call, returning a deterministic Ed25519-signed result.

## Facts

- Endpoint: POST https://rpc-erc20-balance.hergertsynthora.com/service
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synthora-erc-20-token-balance-lookup-3306a89c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZTAiOsImUIFsTjEnqTmN9

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 synthora-erc-20-token-balance-lookup-3306a89c -d '<json body>'
```

Example prompt: What's the current USDC balance of wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Base — I need the signed result I can verify cryptographically.

## When to prefer this

Choose this endpoint when you need a cryptographically signed (Ed25519), verifiable ERC-20 token balance that can be audited or passed to downstream verification logic. Prefer it over raw RPC calls when you want a trustless, signed attestation of a balance rather than a raw unsigned JSON-RPC response. Well-suited for agents operating on Base or other EVM chains needing low-cost ($0.003 USDC) on-chain balance lookups with payment via x402 protocol.

## Known failure modes

- Invalid or malformed wallet address returns an error response
- Unsupported chain identifier causes lookup failure
- Token contract address not found or not a valid ERC-20 results in error
- Upstream RPC node failure — no charge applied per service policy
- Missing required fields (chain, token, address) causes validation error

## How this service works

ERC-20 token balance for a holder via balanceOf. Deterministic, Ed25519-signed.

## Output

Returns the ERC-20 token balance for the specified holder address on the given chain, deterministically computed from on-chain balanceOf, and signed with Ed25519 for verifiability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "token",
  "address"
 ],
 "properties": {
  "chain": {
   "type": "string",
   "description": "chain"
  },
  "token": {
   "type": "string",
   "description": "token"
  },
  "address": {
   "type": "string",
   "description": "address"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synthora-erc-20-token-balance-lookup-3306a89c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from rpc-erc20-balance.hergertsynthora.com](https://www.zero.xyz/host/rpc-erc20-balance.hergertsynthora.com/llms.txt)