Introduction

VerifNow is a validation API for the fields billing and onboarding forms depend on: EU VAT numbers, IBANs, national tax and social identifiers, emails and phone numbers. One API key, one quota, one invoice — instead of three vendors for three fields.

It is built for the developer on the other side of a checkout or a signup form, who has to decide in real time whether to accept what a user just typed.

Why data validation?

Bad data costs money at the point it enters your system:

• An unverified VAT number means reverse-charge invoicing you cannot defend in an audit
• A mistyped IBAN means a transfer that fails days later, with a returned-payment fee
• Disposable addresses inflate your user counts with fake accounts
• Typos frustrate users who genuinely want to sign up — and a typo like gmial.com resolves to a real domain, so it looks deliverable
• Invalid phone numbers lead to failed communications

VerifNow catches these at the point of entry, while the user is still in front of the form.

How it works

VerifNow performs a multi-layer validation pipeline. For email validation, the following checks are performed:

Base URL

All validation requests are made to:

https://api.verifnow.io/api/v1/validate

Validation endpoints

All endpoints accept a POST request with a JSON body containing the value to validate:

{
  "value": "user@example.com"
}

Authentication

VerifNow uses API key authentication. Every request must include your API key in the X-API-KEY header.

X-API-KEY: your_api_key_here

Getting your API key

1. Sign up at app.verifnow.io 
2. Navigate to Settings → API Keys
3. Click Create new key
4. Copy the key — it will only be shown once

Store it as an environment variable:

# .env.local
VERIFNOW_API_KEY=your_api_key_here

Plans & quotas

• FREE plan: requests are blocked once the limit is reached. FREE runs the same STANDARD validation depth as STARTER — see Validation depth by plan.
• Paid plans (STARTER, GROWTH, PRO): requests above the quota are billed per unit at the end of the billing period.
• Concurrent requests: all plans enforce a maximum number of simultaneous requests. Exceeding this returns a 429 error. On non-PRO plans, a 429 can also happen temporarily because of shared server-side concurrency protection, even if you are still within your documented per-plan limit.
• Quota reset: quotas are reset at the start of each billing period (e.g., if your subscription started on the 4th, quotas reset every 4th of the month for a monthly subscription).

See Rate Limits for more details.

Response format

All validation responses share a common structure:

{
  "valid": true,
  "message": "Email address is valid but has risk factors",
  "normalizedValue": "user@example.com",
  "originalValue": "user@example.com",
  "validationLevel": "PREMIUM"
}

For email validations, an additional emailDetails field is included:

{
  "valid": true,
  "message": "Email address is valid but has risk factors",
  "normalizedValue": "user@example.com",
  "originalValue": "user@example.com",
  "validationLevel": "PREMIUM",
  "emailDetails": {
    "signals": {
      "syntax_valid": true,
      "mx_valid": true,
      "typo_detected": false,
      "suggested_domain": null,
      "disposable": false,
      "role_based": false,
      "free_provider": false,
      "domain_age_days": 11554,
      "mx_provider": "google",
      "mx_quality_score": 0.9
    },
    "risk_score": 30,
    "risk_level": "MEDIUM",
    "deliverability": "RISKY",
    "applied_level": "PREMIUM"
  }
}

Key fields

Risk levels (email)

Deliverability values (email)

valid is false only for invalid syntax, a domain with no mail records, or a blocked domain. Risk signals affect deliverability and risk_score, never valid, and the verdict is the same on every plan.

SDKs & libraries

Node.js and TypeScript

npm install @verifnow/sdk

Typed methods for all seven rules, no runtime dependencies, ESM and CommonJS. It throws a typed error when the API is unreachable rather than reporting an unverified value as valid.

• 📦 @verifnow/sdk on npm
• 💻 verifnow-node  on GitHub

Java and Spring Boot

<dependency>
    <groupId>io.verifnow</groupId>
    <artifactId>verifnow-spring-boot-starter</artifactId>
    <version>2.7.0</version>
</dependency>

Auto-configured beans and Jakarta Bean Validation annotations (@VerifNowEmail, @VerifNowIban…).

• 📦 io.verifnow:verifnow-spring-boot-starter on Maven Central
• 💻 verifnow-spring  on GitHub
• 📖 Example project 

For other languages, use the REST API directly — it’s just a few lines of code. See the Examples section.

Support

• 📧 Email: support@verifnow.io