⚡ FadSync Email Validator for Flutter #

The official Flutter & Dart SDK for FadSync MailCheck.

Protect your mobile & web apps from fake signups, disposable/burner emails, mistyped addresses, and fraudulent accounts in 1 single line of code.

✨ Features #

• ⚡ Blazing Fast Validation (<50ms): Sub-second RFC syntax verification, MX lookup via DNS-over-HTTPS, and fraud score analysis.
• 🚫 40M+ Disposable Domains Blocked: Instant detection of temporary and burner mail services (10minutemail, GuerrillaMail, Mailinator, etc.) across 40M+ disposable domains.
• 💡 Smart Typo Autocorrect: Suggests fixes for common domain typos (e.g. user@gamil.com ➔ user@gmail.com) with 1-tap chip replacement.
• 🛡️ 1-Click Auth Guard: Pre-flight your signup & login flows before persisting users to Firebase, Supabase, Appwrite, or custom Postgres/MongoDB databases.
• 🎨 Drop-in UI Widgets: Includes EmailValidatorFormField with real-time async debounce, animated progress spinner, and friendly validation error messages.
• 🧠 In-Memory Smart Cache: Automatically caches repeated checks to save API quota and boost UI responsiveness.

🚀 Quickstart in 30 Seconds #

1. Install the Package #

Add fadsync_email_validator to your pubspec.yaml or run in terminal:

flutter pub add fadsync_email_validator

2. Get Your Free API Key #

1. Sign up at mailcheck.fadsync.com.
2. Copy your API Key from your developer dashboard.

3. Verify an Email Address #

import 'package:fadsync_email_validator/fadsync_email_validator.dart';

void main() async {
  // Initialize client with your API key
  final validator = FadSyncEmailValidator(apiKey: 'YOUR_API_KEY');

  // Verify any email address
  final result = await validator.verify('user@trashmail.com');

  if (result.isSafeToRegister) {
    print('✅ Safe to register: ${result.email}');
  } else {
    print('❌ Blocked: ${result.userFriendlyMessage}');
    // Output: "Temporary and disposable email addresses are not permitted. Please use a permanent email."
  }
}

🔒 1-Click Secure Signup & Login Flow #

Use FadSyncAuthGuard to wrap your user registration flow. It blocks disposable emails and ensures that only valid, deliverable addresses reach your database.

import 'package:flutter/material.dart';
import 'package:fadsync_email_validator/fadsync_email_validator.dart';

final validator = FadSyncEmailValidator(apiKey: 'YOUR_API_KEY');

Future<void> handleUserSignUp(BuildContext context, String email, String password) async {
  await FadSyncAuthGuard.protect(
    client: validator,
    email: email,
    // Triggered only when the email is clean, deliverable, and safe
    onAllowed: (result) async {
      // 💾 Save user to Firebase / Supabase / Backend database
      await databaseService.createUser(
        email: result.email,
        password: password,
      );
      
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Account created successfully! 🎉')),
      );
    },
    // Triggered when email is disposable, invalid, or high-risk
    onBlocked: (errorMessage, result) {
      showDialog(
        context: context,
        builder: (ctx) => AlertDialog(
          title: const Text('Invalid Email'),
          content: Text(errorMessage), // e.g. "Temporary emails are not permitted."
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(ctx),
              child: const Text('OK'),
            ),
          ],
        ),
      );
    },
    // Optional: Prompt user if they made a common domain typo (e.g. @gmai.com)
    onTypoFound: (suggestedEmail, result) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text('Did you mean $suggestedEmail?'),
          action: SnackBarAction(
            label: 'Fix',
            onPressed: () => emailController.text = suggestedEmail,
          ),
        ),
      );
    },
  );
}

🎨 Drop-in UI Widget: EmailValidatorFormField #

Replace standard TextFormField with EmailValidatorFormField to get automatic debounced real-time validation, animated spinner, status checkmark, and autocorrect chip:

EmailValidatorFormField(
  client: validator,
  controller: emailController,
  triggerMode: ValidationTriggerMode.onChangedDebounced,
  debounceDuration: const Duration(milliseconds: 500),
  showTypoSuggestion: true,
  decoration: InputDecoration(
    labelText: 'Business Email',
    hintText: 'alex@company.com',
    border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
  ),
  onValidated: (result) {
    print('Risk Score: ${result.riskScore}, Is Disposable: ${result.isDisposable}');
  },
)

⚙️ Custom Validation Strictness & Rules #

You can adjust the strictness presets or customize individual scoring parameters:

// Strict preset for banking / payment apps
final result = await validator.verify(
  'sales@tempmail.com',
  options: ValidationOptions.strict, // Blocks disposable + role accounts + strict score < 50
);

// Custom criteria
final customOptions = ValidationOptions(
  strictness: StrictnessLevel.medium,
  maxAllowedRiskScore: 60,  // Block if risk score exceeds 60/100
  blockDisposable: true,    // Block 10minutemail, etc.
  blockRoleAccounts: false, // Allow info@, support@
  timeout: const Duration(seconds: 5),
);

📊 Result Model Reference (ValidationResult) #

🛡️ Exception Handling #

try {
  final result = await validator.verify(email);
} on FadSyncAuthException {
  print('Invalid or expired FadSync API Key.');
} on FadSyncRateLimitException {
  print('Rate limit exceeded (HTTP 429).');
} on FadSyncNetworkException {
  print('Network timeout or offline.');
} on FadSyncApiException catch (e) {
  print('API error code: ${e.statusCode}');
}

📄 License #

This SDK is open-source software licensed under the MIT License. Built with 💙 by the FadSync Team.