Quickstart

Signitize checks the email address a user types into your signup form, before you create the account. One request returns three fields:

Field	Problem it solves
email	One account per inbox. The canonical email: every alias of one inbox gives the same value.
disposable	No throwaway signups. true for temporary and throwaway mail domains.
deliverable	No mistyped or made-up addresses. false when the address can never receive mail.

1. Get an API key

1. Click Get API key at the top of this page, or go to Pricing and pick a plan.
2. Enter your name and email. We send you a one-time link.
3. Open the link and click Reveal my API key. Copy the key right away: it is shown only once and we do not store it.

Keys look like sk_live_7Hq2LmX9pR4tVb8Kc1NwZ3yF6dJs0GaE5uQoWiTn. Keep yours on your server, for example in an environment variable called SIGNITIZE_API_KEY. Never ship it in browser or mobile app code.

2. Make your first request

Send the address to POST https://api.signitize.io/v1/check:

cURL

curl https://api.signitize.io/v1/check \
  -H "Authorization: Bearer $SIGNITIZE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email":"[email protected]"}'

Node.js

// Node.js 18+ (built-in fetch)
const response = await fetch('https://api.signitize.io/v1/check', {
    method: 'POST',
    headers: {
        Authorization: `Bearer ${process.env.SIGNITIZE_API_KEY}`,
        'Content-Type': 'application/json',
    },
    body: JSON.stringify({ email: '[email protected]' }),
    signal: AbortSignal.timeout(5000),
})

const body = await response.json()
console.log(response.status, body)
// 200 { email: '[email protected]', disposable: false, deliverable: true }

Python

import os
import requests

response = requests.post(
    "https://api.signitize.io/v1/check",
    headers={"Authorization": f"Bearer {os.environ['SIGNITIZE_API_KEY']}"},
    json={"email": "[email protected]"},
    timeout=5,
)

body = response.json()
print(response.status_code, body)
# 200 {'email': '[email protected]', 'disposable': False, 'deliverable': True}

3. Read the response

{ "email": "[email protected]", "disposable": false, "deliverable": true }

• email is the canonical email. Store it in a unique column of your users table.
• disposable: true means a throwaway domain. Reject the signup.
• deliverable: false means the address can never receive mail. Ask the user to fix it.

Then send your usual verification email to the address the user typed, not to email.

:::danger Before you go live

If Signitize is slow or down, your signup must still succeed. Use a 5-second timeout, create the account as pending when Signitize doesn't answer, and recheck it later: Never block a signup.

:::

Next steps

• Never block a signup: keep your signup working during outages, and recheck those users afterwards. Read this before launch.
• Check an email: the fields, examples and how to use the result in your signup flow.
• Rate limits & usage headers: the monthly quota, the per-second limit and what counts as a check.
• API reference: try the API live from your browser with your key.