# SALT19 Agent Utility Grid – Base Token Balance Lookup

> SALT19 Agent Utility Grid – Base Token Balance Lookup is a paid API for AI agents from api.salt19.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Returns the on-chain ERC-20 token balance for a given wallet address and token contract at the latest block.

## Facts

- Endpoint: POST https://api.salt19.com/v1/base-token-balance
- 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/salt19-agent-utility-grid-base-token-balance-lookup-6c5481f6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_gLW3QQQ_Zw36Y8UzGny0B

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 salt19-agent-utility-grid-base-token-balance-lookup-6c5481f6 -d '<json body>'
```

Example prompt: What's the current on-chain USDC balance for wallet 0xAbC123...4567, using token contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48?

## When to prefer this

Use this endpoint when you need a fast, pay-per-call on-chain ERC-20 balance lookup with no API key setup, accessible via the x402 micropayment protocol. It is particularly suited for AI agents in the SALT19 / Agent Utility Grid ecosystem that already handle x402 payments natively. Prefer it over free RPC calls when you want a managed, low-friction single endpoint that abstracts away node infrastructure.

## Known failure modes

- Invalid Ethereum address format for owner or token_address — returns validation error
- Token contract address is not an ERC-20 contract — may return zero balance or error
- Wallet has no balance for the token — returns balance_atomic: '0' (not an error)
- Network congestion or RPC unavailability — may result in timeout or 5xx response
- Payment not completed (x402 protocol) — request blocked until 0.01 USDC fee is paid

## How this service works

SALT19 is an independent applied AI systems lab behind EvoMind governed cognition, the MCP-native Agent Utility Grid, the ARCS research community, AeroClear UAS flight intelligence, and practical software for real-world work.

## Output

Returns a JSON object with the token symbol (e.g. 'USDC'), decimal precision (e.g. 6), the block number at which the balance was read, and the balance in atomic (smallest) units as a string (e.g. '1000000' for 1 USDC). The agent must divide the atomic balance by 10^decimals to get the human-readable amount.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "owner": {
   "type": "string",
   "pattern": "^0x[0-9a-fA-F]{40}$"
  },
  "token_address": {
   "type": "string",
   "pattern": "^0x[0-9a-fA-F]{40}$"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "symbol": "USDC",
  "decimals": 6,
  "block_number": 12345678,
  "balance_atomic": "0"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/salt19-agent-utility-grid-base-token-balance-lookup-6c5481f6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.salt19.com](https://www.zero.xyz/host/api.salt19.com/llms.txt)