# x402 Format Checker – Email Validation

> x402 Format Checker – Email Validation is a paid API for AI agents from validate.crewofthecaptain.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-12).

Validates the format and syntax of an email address and returns a validity flag, reason, and normalized form, paid per-call via x402 in USDC.

## Facts

- Endpoint: POST https://validate.crewofthecaptain.com/api/validate/email?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-format-checker-email-validation-c0938e24
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vGq-YaoG89akOs9NQOUUF

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-format-checker-email-validation-c0938e24 -d '<json body>'
```

Example prompt: Can you check whether 'user.name+tag@example.co.uk' is a valid email address and give me its normalized form?

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-use email format and syntax validator with no subscription required — ideal for low-volume checks, agent workflows, or pipelines where you want to pay only for what you use via crypto microtransaction. Prefer this over heavyweight email deliverability services when you only need format/syntax validation, not MX-record or SMTP-level reachability checks.

## Known failure modes

- Missing or empty 'value' field returns a validation error
- Input exceeding 512 characters may be rejected
- Malformed JSON body returns a 400-level error
- x402 payment failure or insufficient USDC balance returns a 402 Payment Required response
- Non-email strings (e.g. IBANs, phone numbers) will return valid:false with an appropriate reason

## How this service works

Format and checksum validation for IBAN, EU VAT, Polish NIP/REGON/PESEL and email, pay-per-call via x402. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.

## Output

A JSON object with: 'type' (always 'email'), 'valid' (boolean indicating whether the address passes format and syntax checks), 'reason' (string explaining the outcome, e.g. 'ok' or a specific error), and 'normalized' (the canonicalized form of the email address).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "value": {
   "type": "string",
   "maxLength": 512
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "type": "email",
  "valid": true,
  "reason": "ok",
  "normalized": "…"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-format-checker-email-validation-c0938e24/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from validate.crewofthecaptain.com](https://www.zero.xyz/host/validate.crewofthecaptain.com/llms.txt)