x402 Format Checker MCP Server

by crewofthecaptain Your server? Claim it

answering

x402 Format Checker is answering right now. Last checked 2 min ago. It exposes 7 tools.

IBAN, EU VAT, NIP, REGON, PESEL, email checks. Only $0.001 (0.1 cent) per check via x402 on Base

Uptime history 6 days of history

6 days agonow

100.0%

Uptime 24h

92 of 92 checks

Tools

read from the server

170 ms

Response time

average over 24h

open, no key

Access

streamable-http

Nothing serious here today

Today is the operative word: we check x402 Format Checker every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 2 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add format-checker --transport http https://validate.crewofthecaptain.com/mcp

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "format-checker": {
      "url": "https://validate.crewofthecaptain.com/mcp"
    }
  }
}

~/.codex/config.toml

[mcp_servers.format-checker]
url = "https://validate.crewofthecaptain.com/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "format-checker": {
      "url": "https://validate.crewofthecaptain.com/mcp"
    }
  }
}

.vscode/mcp.json

{
  "mcpServers": {
    "format-checker": {
      "url": "https://validate.crewofthecaptain.com/mcp"
    }
  }
}

Available tools 7

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

validate

validate_email

Email address syntax (dot-atom local part, LDH domain; no DNS). Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. Returns {type, valid, normalized, reason}; the input is never echoed or stored and personal identifiers are masked.

validate_eu_vat

EU VAT number: per-country format (offline, no VIES); PL also NIP checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. Returns {type, valid, normalized, reason}; the input is never echoed or stored and personal identifiers are masked.

validate_iban

IBAN: country length + ISO 13616 mod-97 checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. Returns {type, valid, normalized, reason}; the input is never echoed or stored and personal identifiers are masked.

validate_pl_nip

Polish NIP tax id: 10 digits + weighted mod-11 checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. Returns {type, valid, normalized, reason}; the input is never echoed or stored and personal identifiers are masked.

validate_pl_pesel

Polish PESEL: checksum + encoded birth date and sex. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. Returns {type, valid, normalized, reason}; the input is never echoed or stored and personal identifiers are masked.

validate_pl_regon

Polish REGON: 9 or 14 digits + mod-11 checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. Returns {type, valid, normalized, reason}; the input is never echoed or stored and personal identifiers are masked.

types

list_types

List the available checks, price, network and payment details (free). Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.

Endpoints

URL	Transport	State	Latency	Checked
https://validate.crewofthecaptain.com/mcp	streamable-http	answering	173 ms	2 min ago

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x402 Format Checker — questions

Answers built from our own checks of this server.

What can x402 Format Checker do?

It exposes 7 tools, read directly from the server on our last check. Among them: list_types, validate_email, validate_eu_vat, validate_iban, validate_pl_nip, validate_pl_pesel and 1 more. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is x402 Format Checker working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 92 of 92 checks got a reply (100.0%), average response time 170 ms. The bar chart above shows every period we have measured.

How do I connect x402 Format Checker?

Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does x402 Format Checker need an API key?

No. x402 Format Checker completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 7 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is x402 Format Checker?

It answers our handshake in 170 ms on average, which is faster than 69% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.