# Ethereum/Base Address Classifier

> Ethereum/Base Address Classifier is a paid API for AI agents from build-4c941cab041172e9439ece2f.emblem.build, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Classifies an Ethereum or Base address as contract vs. EOA, checks for bytecode presence, and resolves ENS names, paid per-call in USDC onchain.

## Facts

- Endpoint: POST https://build-4c941cab041172e9439ece2f.emblem.build/pub/tasks/x402-onchain/api/address
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ethereum-base-address-classifier-4a99f56f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KcpTF-o-4RE313sqFBLcN

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 ethereum-base-address-classifier-4a99f56f -d '<json body>'
```

Example prompt: Is the address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Ethereum a smart contract or a regular wallet, and can you resolve its ENS name?

## When to prefer this

Choose this endpoint when you need a fast, single-call classification of any EVM address (Ethereum or Base) as contract vs. EOA, with bytecode presence detection and optional ENS resolution, paid trustlessly per-call in USDC. Prefer it over manual RPC calls when you want a clean, agent-ready JSON response without managing your own node or provider credentials.

## Known failure modes

- Invalid or malformed Ethereum address returns a validation error
- Address not found on the specified chain returns no-code/EOA result
- ENS resolution failure if no reverse record is set
- Payment failure if USDC onchain payment is not completed via x402
- Unsupported chain identifier returns an error
- Network or RPC timeout causes request failure

## How this service works

Address label/classify on Base/Ethereum: contract-vs-EOA + code presence (+ENS). Onchain USDC pay-per-call.

## Output

Returns a classification of the given address indicating whether it is a smart contract or an externally owned account (EOA), whether bytecode is present at that address, and any resolved ENS name associated with it.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ethereum-base-address-classifier-4a99f56f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from build-4c941cab041172e9439ece2f.emblem.build](https://www.zero.xyz/host/build-4c941cab041172e9439ece2f.emblem.build/llms.txt)