# x402 Trust & Discovery API — Onchain Token Balance Lookup

> x402 Trust & Discovery API — Onchain Token Balance Lookup is a paid API for AI agents from gkyf2bs3b4p35hwwg5zzsnejeu.srv.us, paid per call via x402, $0.001/call, status down (last checked 2026-10-01).

Returns the onchain ERC-20 token balance (defaulting to USDC on Base) for a given wallet address, without requiring any payment credentials.

## Facts

- Endpoint: GET https://gkyf2bs3b4p35hwwg5zzsnejeu.srv.us/v1/onchain/balance?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-trust-discovery-api-onchain-token-balance-lookup-67cae9a4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EWwGky6aqSy-3-nfVuyhS

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 x402-trust-discovery-api-onchain-token-balance-lookup-67cae9a4
```

Example prompt: What's the current USDC balance on Base for wallet address 0x1234...abcd?

## When to prefer this

Use this endpoint when you need a keyless, read-only onchain balance check for any ERC-20 token on Base — especially USDC — without needing to sign a transaction or hold any credentials. Ideal as a pre-flight check before attempting an x402 micropayment to confirm a wallet has sufficient funds.

## Known failure modes

- Invalid or malformed 0x address returns an error or zero balance
- Unsupported token contract address may return zero or an error
- Network latency or Base RPC unavailability causes a timeout
- Empty response schema means the exact error structure is undocumented

## How this service works

Independent pre-purchase safety and reputation checks for x402 and MPP endpoints, plus keyless onchain data on Base. Accepts BOTH EIP-3009 and Circle Gateway credentials — only 141 of 788 Base-payable resources do, and a single-credential buyer is locked out of 53.8% of this market on one rail or 28.3% on the other. GET /v1/guard?url=&credential= answers whether the credential you carry can pay a given endpoint at all, before you try. Searching this market for "is this API endpoint a scam" returns registries and explorers but no dedicated service; that gap is what /v1/guard fills, inspecting an endpoint WITHOUT paying it and returning a go / test-with-minimum / do-not-pay verdict backed by onchain settlement history.

## Output

Returns a JSON object containing the onchain ERC-20 token balance for the specified wallet address on Base, defaulting to the USDC contract if no token address is supplied. The response reflects the current confirmed balance as readable from the Base blockchain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "token": {
   "type": "string",
   "description": "ERC-20 contract address. Defaults to USDC on Base."
  },
  "address": {
   "type": "string",
   "description": "0x address to read balances for."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {}
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-trust-discovery-api-onchain-token-balance-lookup-67cae9a4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from gkyf2bs3b4p35hwwg5zzsnejeu.srv.us](https://www.zero.xyz/host/gkyf2bs3b4p35hwwg5zzsnejeu.srv.us/llms.txt)