# Agent402 UK Ethereum Address Validator

> Agent402 UK Ethereum Address Validator is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).

Validates that a string is a correctly formatted Ethereum address (0x + 40 hex chars) and returns its lowercase-normalized form

## Facts

- Endpoint: POST https://agent402.co.uk/v1/utils/eth-address
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-uk-ethereum-address-validator-1ac39fe7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-JrfQ1CFCnaVfGqqzN--g

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 agent402-uk-ethereum-address-validator-1ac39fe7 -d '<json body>'
```

Example prompt: Before we proceed with the on-chain transfer, can you check whether '0x9eF92B278a3867C429751390Ec427736Eb4baBB2' is a valid Ethereum address and give me its normalized lowercase form?

## When to prefer this

Use this endpoint as a lightweight format gate immediately before any on-chain Ethereum operation, user input acceptance, or address storage step. Prefer it over rolling your own regex validation to ensure consistent hex-format and length rules. It also normalizes casing, reducing downstream checksum errors. Not a substitute for on-chain account existence checks or EIP-55 checksum validation — use it purely for structural format gating.

## Known failure modes

- Address missing '0x' prefix — valid returns false
- Address has wrong length (not 40 hex chars after 0x) — valid returns false
- Address contains non-hex characters — valid returns false
- Malformed or missing 'address' field in request body — likely 400 error
- Empty string input — valid returns false

## How this service works

Don't burn tokens on deterministic work. Go/no-go jobs first: payout preflight, text firewall (PII/secrets), budget check — then rails, calendars, finmath. x402 USDC on Base. UK + global. agent402.co.uk — not agent402.tools. $0.001–$0.002 USDC on Base. No API keys.

## Output

Returns a JSON object with a 'valid' boolean indicating whether the input conforms to the Ethereum address format (0x followed by exactly 40 hexadecimal characters), and a 'normalized' field containing the lowercase version of the address if valid.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "address": {
   "type": "string",
   "description": "0x address"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "valid": true,
  "normalized": "0x9ef92b278a3867c429751390ec427736eb4babb2"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-uk-ethereum-address-validator-1ac39fe7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.co.uk](https://www.zero.xyz/host/agent402.co.uk/llms.txt)