# x402-gateway: wallet_checksum

> x402-gateway: wallet_checksum is a paid API for AI agents from x402.freeq.one, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Converts an Ethereum address to its EIP-55 checksummed form for use in SIWE (Sign-In With Ethereum) messages and other standards requiring checksummed addresses.

## Facts

- Endpoint: POST https://x402.freeq.one/tools/wallet_checksum
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-gateway-wallet-checksum-e1089349
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_wMpWXsaCPw5qhLxWkS81z

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-gateway-wallet-checksum-e1089349 -d '<json body>'
```

Example prompt: Can you convert this Ethereum address to its EIP-55 checksummed form? The address is 0xd8da6bf26964af9d7eed9e03e53415d37aa96045 — I need the properly checksummed version for a SIWE message.

## When to prefer this

Use this endpoint when you need a quick, pay-per-use EIP-55 address checksum without setting up local libraries or managing API keys. Especially useful in agentic workflows that need to prepare addresses for SIWE authentication messages, where the checksummed form is required on line 2 of the message before signing.

## Known failure modes

- Invalid or malformed Ethereum address input returns an error
- Non-Ethereum addresses (e.g. Solana, Bitcoin) are not supported
- Payment failure if insufficient USDC balance for the $0.001 per-call fee
- Incorrect body format (missing required fields) results in a schema validation error

## How this service works

x402-gateway tool: wallet_checksum — Convert an Ethereum address to its EIP-55 checksummed form. SIWE messages require the checksummed address on line 2 before signing.

## Output

Returns the EIP-55 checksummed Ethereum address as a string with proper mixed-case encoding (e.g. 0xD8dA6BF26964aF9D7eEd9e03E53415D37aA96045), which can be directly used in SIWE messages or any context requiring a standards-compliant Ethereum address.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "address": {
   "type": "string",
   "description": "Ethereum address in any casing (0x...)"
  }
 }
}
```

## Response schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-gateway-wallet-checksum-e1089349/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.freeq.one](https://www.zero.xyz/host/x402.freeq.one/llms.txt)