# SALT19 Base Contract State Lookup

> SALT19 Base Contract State Lookup is a paid API for AI agents from api.salt19.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Retrieves the base on-chain state of an Ethereum address, including whether it is a contract, its bytecode size, and current block context.

## Facts

- Endpoint: POST https://api.salt19.com/v1/base-contract-state
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/salt19-base-contract-state-lookup-ba0cc7d7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ygh1cmwjIG9fVXMvrc95q

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-base-contract-state-lookup-ba0cc7d7 -d '<json body>'
```

Example prompt: Can you check whether 0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984 is a smart contract on-chain and tell me its bytecode size and what block we're at?

## When to prefer this

Use this endpoint when you need a fast, cheap ($0.01 USDC) on-chain lookup of an Ethereum address's base state — specifically whether it is a contract, its bytecode footprint, and the current block. Prefer this over full blockchain explorers when you only need contract/EOA classification and bytecode size without full ABI decoding, event logs, or transaction history. Ideal for agent workflows that gate logic on whether an address is a contract before taking further action.

## Known failure modes

- Invalid address format (not a valid 0x hex address) — request rejected before on-chain query
- Address not found or network unavailable — may return is_contract false or error
- Payment failure via x402 protocol — call not processed if USDC payment of $0.01 not confirmed
- Rate limiting or quota exceeded — HTTP 429 or similar
- Node RPC failure — upstream blockchain node unavailable causing 5xx response

## 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 containing: whether the address is a smart contract (is_contract boolean), the size of its deployed bytecode in bytes (code_bytes), the current block number (block_number), and token context including symbol (USDC) and decimals (6).

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "token": {
   "symbol": "USDC",
   "decimals": 6
  },
  "code_bytes": 1234,
  "is_contract": true,
  "block_number": 12345678
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/salt19-base-contract-state-lookup-ba0cc7d7/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)