# FastX402 Lab String Format Validator

> FastX402 Lab String Format Validator is a paid API for AI agents from fastx402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-17).

Validates a string against one of 33 named formats (email, URL, UUID, IP addresses, IBAN, JWT, crypto addresses, ISO dates, and more) using validator.js rules

## Facts

- Endpoint: GET https://fastx402.tools/validate?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastx402-lab-string-format-validator-e4cc0b36
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_y-SXrQmRpO49WH4nZ3mRP

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 fastx402-lab-string-format-validator-e4cc0b36
```

Example prompt: Is 'user@example.com' a valid email address? Run it through the validator.js-based format checker and tell me if it passes.

## When to prefer this

Use this endpoint when you need quick, authoritative format validation using well-established validator.js rules across 33 different format types — especially for formats like IBAN, BIC, EAN, ISBN, ISSN, magnet URIs, locales, and crypto addresses that are complex to implement correctly from scratch. Prefer this over rolling your own regex when correctness and coverage across many formats matters.

## Known failure modes

- Invalid or unsupported format type enum value returns an error
- Empty or missing 'value' query parameter returns an error
- Missing 'type' query parameter returns an error
- Payment failure returns 402 Payment Required
- Network timeout on the x402 payment flow

## How this service works

146 pay-per-call tools for AI agents, from $0.001 per request in USDC on Base or Solana with x402. No account, no API key.

## Output

Returns a JSON object with two fields: 'type' (the format name that was checked, e.g. 'email') and 'valid' (a boolean indicating whether the input string conforms to that format's rules).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "value",
      "type"
     ],
     "properties": {
      "type": {
       "enum": [
        "email",
        "url",
        "uuid",
        "ipv4",
        "ipv6",
        "cidr",
        "mac",
        "fqdn",
        "isbn",
        "issn",
        "iban",
        "bic",
        "ean",
        "jwt",
        "semver",
        "hex_color",
        "mime_type",
        "lat_long",
        "port",
        "md5",
        "sha256",
        "base64",
        "base58",
        "json",
        "slug",
        "eth_address",
        "btc_address",
        "iso8601",
        "country_code",
        "currency_code",
        "locale",
        "magnet_uri",
        "time"
       ],
       "type": "string",
       "description": "Format to check"
      },
      "value": {
       "type": "string",
       "description": "The string to check"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "type": {
       "type": "string"
      },
      "valid": {
       "type": "boolean"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "type": "email",
  "valid": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastx402-lab-string-format-validator-e4cc0b36/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fastx402.tools](https://www.zero.xyz/host/fastx402.tools/llms.txt)