Documentation

API Reference

The usecheck API lets you validate email addresses and domains in real time. All endpoints require authentication via API key.

Authentication

Include your API key in the Authorization header:

Authorization: Bearer uc_live_abc123...

Get your API key from the dashboard. Free tier includes 1,000 requests/month.

Base URL

https://api.usecheck.sh

GET/v1/email/:email

Validate an email address

Parameters

emailstringThe email address to validate

Response

{
  "status": 200,
  "email": "test@mailinator.com",
  "domain": "mailinator.com",
  "mx": true,
  "mx_records": [
    "mx1.mailinator.com"
  ],
  "disposable": true,
  "public_domain": false,
  "relay_domain": false,
  "role_account": false,
  "alias": false,
  "spam": true,
  "domain_age_days": 4523,
  "did_you_mean": null,
  "blocklisted": false
}

GET/v1/domain/:domain

Validate a domain

Parameters

domainstringThe domain to validate

Response

{
  "status": 200,
  "domain": "mailinator.com",
  "mx": true,
  "mx_records": [
    "mx1.mailinator.com"
  ],
  "disposable": true,
  "public_domain": false,
  "relay_domain": false,
  "spam": true,
  "domain_age_days": 4523
}

Response Fields

Full reference of all fields returned by the email validation endpoint.

statusnumberHTTP status code (200 or 400)

emailstringThe normalized email address

domainstringThe email domain

mxbooleanWhether the domain has valid MX records

mx_recordsstring[]List of MX records for the domain

disposablebooleanWhether the domain is a disposable/throwaway email provider

public_domainbooleanWhether the domain is a public email provider (Gmail, Yahoo, etc.)

relay_domainbooleanWhether the domain is an email relay/forwarding service

role_accountbooleanWhether the local part is a role account (admin@, info@, etc.)

aliasbooleanWhether the email uses plus-addressing or is an alias

spambooleanWhether the email is likely spam (disposable or very new domain)

domain_age_daysnumber | nullDomain age in days, or null if unknown

did_you_meanstring | nullSuggested correction for common typos (gmial.com → gmail.com)

blocklistedbooleanWhether the domain is on your custom blocklist

Rate Limits

Rate limits depend on your plan. The response includes rate limit headers:

X-RateLimit-LimitMax requests per second

X-RateLimit-RemainingRemaining requests in current window

X-RateLimit-ResetUnix timestamp when the window resets

Errors

The API returns standard HTTP status codes.

400Invalid email syntax or missing parameter

401Missing or invalid API key

429Rate limit exceeded

500Internal server error