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From the maintainer of node-email-verifier, trusted by developers with 100,000+ weekly downloads.

The email validation API
for signup flows

Catch typos, disposable emails, and broken domains at signup before they become junk accounts, failed confirmations, or wasted onboarding steps.

1,000 free validations/month
No credit card required
2-minute integration

Try it live

See why [email protected] isn't a typo. Get real-time validation data instantly.

Try these examples:

Response

Enter an email address to see the validation response...

Why ValidKit?

Purpose-built for signup flows, from solo projects to high-traffic production apps.

Intelligent Validation Engine

Goes beyond regex with syntax, DNS, MX, and disposable checks. Understands developer patterns like [email protected] and plus addressing, so your CI pipelines and staging environments stay stable.

<200ms Median Response

Fast enough for synchronous signup flows. <200ms median with intelligent caching means validation completes before the user notices. Calculate your ROI →

One Call to Integrate

REST API and official TypeScript/Python SDKs. Add validation to Clerk, Auth0, Supabase, Firebase, or your custom signup backend with a single call.

Built for Signup Flows

Purpose-built for real-time signup and onboarding validation. Catch typos, disposables, and invalid domains at registration before they become junk accounts or bounced emails.

Reliable at Scale

Built on production-grade infrastructure. From your first signup form to millions of validations, it just works. View status →

GDPR Compliant

Real-time validation with a privacy-first posture. Usage logs are private to your account and auto-deleted after 90 days.

Built for your auth and signup stack

Official SDKs for Node.js and Python, plus a simple REST API for any language.

// npm install @validkit/sdk
import { ValidKit } from '@validkit/sdk';
 
const validkit = new ValidKit({ api_key: 'YOUR_API_KEY' });
 
// Validate during signup
const result = await validkit.verifyEmail('[email protected]');
 
console.log(result);

Frequently Asked Questions

Everything you need to know before adding ValidKit to your signup flow.

The free tier includes 1,000 validations per month, full API access, all validation features (syntax, DNS, MX, disposable detection, developer pattern intelligence), and community support. No credit card required to start.

Our infrastructure delivers <200ms median response times through intelligent caching, optimized validation algorithms, and parallel processing. We cache DNS/MX lookups to keep latency consistently low, making us 2-3x faster than the industry average of 200-500ms.

We understand that [email protected], [email protected], and [email protected] are valid patterns in development and production environments. Our purpose-built validation engine recognizes these patterns and validates them appropriately, unlike traditional validators that might flag them as suspicious.

Email addresses appear in your private usage logs for 90 days, then they are automatically deleted. Logs are visible only to your account. We do not share or sell validation data. All validation is processed in real-time. GDPR compliant with built-in data retention and automatic purging, so you do not need to build deletion workflows.

Absolutely. ValidKit works with any authentication provider through our REST API or TypeScript/Python SDKs. Whether you're using Clerk, Auth0, Supabase, Firebase, or a custom solution - add email validation with a single API call or SDK method.

ValidKit validates one email per request in real-time, optimized for signup and onboarding moments. Each validation completes in <200ms median. Fast enough for synchronous form submission. Rate limits scale with your plan: Free (60 req/min), Starter (120 req/min), Growth (600 req/min), providing plenty of headroom for even high-traffic signup forms.

On the free plan, validations pause at the monthly limit until you upgrade. On paid plans, overages are charged automatically so your production signup flows stay unblocked. You stay in control of spend, usage, and scaling.

When the result is ambiguous, ValidKit returns a safe response rather than a false certainty. The risk field in the response (low, medium, high, or unknown) lets you decide: allow the user through, prompt for confirmation, or step up to verification.

ValidKit handles the email-quality layer of signup defense. For more adversarial signup surfaces, pair it with rate limits, CAPTCHA or Turnstile, confirmation gating, or step-up verification.

Still have questions?

The docs, quickstart, and API reference cover the most common questions.

Quickstart GuideContact Us

Ready to protect your signup flow?

Stop junk signups at the source. Keep your user list clean, your onboarding smooth, and your test workflows safe. Start with 1,000 free validations every month.

Get Your Free API KeyQuickstart Guide

No credit card required • Setup in 2 minutes • Cancel anytime

Built with security and privacy in mind. More on Security • GDPR Compliant

Built with security and privacy in mind.More on Security
GDPR Compliant