# Vextorium SIWE Verify

> Vextorium SIWE Verify is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-15).

Verifies a Sign-In with Ethereum (EIP-4361) message and signature, parsing domain, address, chain, nonce, and dates, then confirming authenticity and expiry.

## Facts

- Endpoint: POST https://api.vextorium.com/v1/siwe-verify?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vextorium-siwe-verify-50935c5b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_F7N1NQbwiGDSy0dN-tcPE

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 vextorium-siwe-verify-50935c5b -d '<json body>'
```

Example prompt: Can you verify this Sign-In with Ethereum login? The message is '{{siwe_message}}' and the wallet signature is '{{signature}}'. Check it against domain example.com and nonce abc12345.

## When to prefer this

Choose this endpoint when you need to verify a Sign-In with Ethereum (EIP-4361) authentication flow — particularly when you want a single call that both parses the structured SIWE message and cryptographically validates the wallet signature, expiry, domain, and nonce in one step without running your own Ethereum node or crypto library. Ideal for dApps, AI agents, or backends that need wallet-based authentication without managing cryptographic primitives directly.

## Known failure modes

- Invalid or malformed SIWE message string returns valid:false with parsing errors
- Signature does not match the address in the message returns valid:false
- Message has passed its expiration date returns valid:false with expiry error
- Domain mismatch when expected domain is provided returns valid:false
- Nonce mismatch when expected nonce is provided returns valid:false
- Missing required fields (message or signature) returns a 4xx error
- Malformed Ethereum signature format causes parsing failure

## How this service works

558 pay-per-call data APIs for AI agents: Solana and EVM on-chain data, tokenized stocks, DeFi, Hyperliquid, economy and official statistics, FX, validation, web and developer tools. Pay in USDC via x402.

## Output

Returns a JSON object with a 'valid' boolean, the parsed wallet address, domain, chain ID, nonce, issued and expiry timestamps, statement, URI, and an errors array listing any validation failures such as bad signature, expired message, or domain mismatch.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "nonce": {
   "type": "string"
  },
  "domain": {
   "type": "string"
  },
  "message": {
   "type": "string"
  },
  "signature": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "uri": "https://example.com",
  "chain": "8453",
  "nonce": "abc12345",
  "valid": true,
  "domain": "example.com",
  "errors": [],
  "issued": "2026-10-02T20:00:00Z",
  "address": "0x7E5F4552091A69125d5DfCb7b8C2659029395Bdf",
  "expires": null,
  "statement": "Sign in"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vextorium-siwe-verify-50935c5b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)