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MailCheckAPI
by FadSync
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40M+ Disposable Domains Blocked • Trusted by 500+ Enterprises

Instantly detect and block temporary, disposable, and burner email addresses in real-time with sub-50ms latency. Prevent fake account creation, reduce bounce rates, and protect your database at the point of signup.

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40 Million+
Domains Blocked
50ms
Avg Response Time
verify_user.js
const response = await fetch('https://api.fadsync.com/v1/verify', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer fs_live_********************',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({ email: 'user@tempmail.ninja' })
});

const data = await response.json();

if (data.is_disposable) {
  console.warn('⛔ Access Denied: Disposable domain detected.');
}
Why MailCheck API?

Stop fake users from destroying your email reputation.

Disposable domains, burner inboxes, and malicious bot signups inflate your infrastructure costs and damage inbox deliverability. MailCheck API by FadSync provides developer-first, real-time email verification to keep your user database authentic.

Real-Time Disposable Detection

Block temporary email services, 10-minute mailboxes, and zero-day burner domains before they reach your database. Our continuously updated algorithms catch stealth disposable providers that static blacklists miss.

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Database & CRM Hygiene

Maintain clean user records and protect your mailing lists from invalid signups. Automatically reduce hard bounces, prevent SaaS free trial abuse, and improve email deliverability without manual review.

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Sub-50ms Edge Latency

Deploy synchronous email validation directly into your registration and checkout flows. Powered by an edge infrastructure optimized for sub-50ms global response times with zero onboarding friction.

View benchmarks
99.99%
Uptime SLA
40M+
Domains Blocked
<50ms
Global Latency
Developer First

Integrate in minutes.
Secure forever.

A lightweight, RESTful email validation API designed to drop into any signup form, onboarding workflow, or backend stack. With ready-to-use SDKs for Node.js, Python, Go, and PHP, you can start detecting disposable email addresses with a single API request.

Node.js
Python
<> Go
PHP PHP
Read the API Docs
MailCheck API - bash
curl -X POST "https://api.fadsync.com/v1/verify" \
  -H "Authorization: Bearer $MAILCHECK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "domain": "malicious-pattern.io" }'
200 OK
124ms
{
  "status": "success",
  "data": {
    "domain": "malicious-pattern.io",
    "is_disposable": true,
    "risk_score": 0.98
  }
}
Developer Wall of Love

Loved by developers. Trusted at scale.

See how backend architects, SaaS founders, and engineering teams protect their user databases and signup pipelines with MailCheck API.

4.9 / 5.0 Rating on RapidAPI
Sub-50ms Global Edge Response
99.99% Guaranteed SLA
Zero-Retention Privacy
Latency: 24ms

"Most email verification APIs add 400ms+ to our signup pipeline. MailCheck API responds in ~25ms from edge nodes. Zero perceptible latency during onboarding."

AR
Alex Rivera
@alex_infra • Backend Infrastructure Lead
Next.js / Edge Runtime
94% Abuse Drop

"We got hit with over 3,500 burner registrations during our Product Hunt launch week. We integrated MailCheck API in 10 lines of code and immediately stopped the spam surge."

SJ
Sarah Jenkins
@sarah_builds • SaaS Founder & CTO
Auth0 & Supabase
100k+ req/day

"Cleanest JSON response format we've worked with. The is_disposable and MX detection flags are deterministic, accurate, and have handled 100k+ daily verifications with zero hiccups."

DK
David Kovacs
@david_scale • Senior Staff Engineer
Go / High-Throughput
Bounce Rate: <0.8%

"Filtering out disposable domains at the moment of signup dropped our email bounce rates from 6.2% down to 0.8%, which protected our sender reputation across all ESPs."

ML
Marcus Lin
@mlin_growth • VP of Growth Engineering
SendGrid & Resend
100% In-Memory

"The in-memory, zero-retention verification policy was critical for our GDPR and security audit. Payload data is processed and instantly discarded without persistent logging."

EP
Elena Pavlova
@elena_sec • Lead Security Architect
Zero-Retention Protocol
Zero Credit Abuse

"We were losing server resources to users recycling disposable emails to farm free trial credits. Adding MailCheck to our auth pipeline stopped multi-account abuse overnight."

TW
Tyler Walsh
@tyler_dev • AI Product Engineer
Stripe & Clerk Auth

Switching from a Legacy Provider?

Engineering teams are migrating to MailCheck API for sub-50ms edge latency, zero-retention privacy, and real-time disposable domain detection. Compare us head-to-head.

ZeroBounce Alternative

Stop waiting 400ms+ for validation. Switch to edge-native architecture that processes requests in RAM.

Sub-50ms Latency

NeverBounce Alternative

Tired of paying for expensive monthly seat locks? Get 100% Zero-Retention privacy on a true pay-per-request model.

Zero-Retention Privacy

Hunter.io Alternative

Don't rely on probabilistic guessing that ruins your sender reputation. Upgrade to deterministic SMTP verification.

40M+ Disposable Domains
View all 10+ competitor comparisons
Transparent Pricing

Predictable pricing for any scale.

Transparent, high-volume email validation pricing. Start for free, upgrade when you need to. No hidden fees, no surprises.

Basic

$0/month

Perfect for testing real-time disposable email verification.

250 requests/month
1 req/sec limit
Standard support
Get API Key
Recommended

Pro

$15/month

For growing SaaS apps needing automated burner domain blocking.

10,000 requests/month
5 req/sec limit
Priority email support
$0.002 overage fee
Upgrade to Pro

Ultra

$49/month

High-velocity verification for scaling production apps.

50,000 requests/month
20 req/sec limit
Priority support
$0.0015 overage fee
Upgrade to Ultra

Mega

$149/month

Maximum throughput with enterprise SLAs and dedicated support.

250,000 requests/month
50 req/sec limit
Dedicated support & Slack
$0.001 overage fee

Need something custom?

We offer tailored infrastructure solutions for specific industry requirements including healthcare (HIPAA) and finance (PCI-DSS) for volumes above 1M requests.

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SOC2 Certified

Enterprise-grade security standards.

Global Edge

Presence in 40+ regions worldwide.

Got Questions?

Everything you need to know.

We maintain a 99.9% accuracy rate by constantly updating our proprietary database of over 40 million known disposable domains, burner inboxes, and temporary MX records. Our real-time algorithms detect subtle patterns and behaviors of emerging throwaway email networks.
Yes! Every developer account gets free validation requests every month with zero commitment. You only need to upgrade if your SaaS signup volume exceeds the free tier limits.
Our global edge network guarantees sub-50ms latency worldwide. This means you can validate emails synchronously during the user signup or checkout flow without adding any friction or delay for legitimate users.
No emails are ever sent. We perform non-intrusive DNS and MX record inspection, syntax validation (RFC 5322), and initiate a socket-level SMTP handshake to confirm the mailbox exists, disconnecting before message transmission so your sender reputation remains completely untouched.
Extremely easy. It is a developer-friendly RESTful JSON API. We offer SDKs for Node.js, Python, Go, and PHP, or you can make a single HTTP POST request from any frontend or backend framework.

Start blocking fake accounts in under 2 minutes.

Join thousands of developers and SaaS founders securing their databases against disposable bot signups. No credit card required to start.

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