The Developer-First Sandbox
for Auth & Email Testing

Stop spamming real users. Automate email verification for your signup, login, and password reset flows. Capture every email from your dev environment with our Sandbox SMTP.

SigninID Sandbox

Powerful Features

Everything you need for email testing

A complete email sandbox with catch-all inbox, SMTP capture, OTP detection, and spam analysis. Built for QA automation and developer workflows.

Catch-All Inbox

Receive real emails from anywhere at any address like *@yourserver.signinid.com. Auto-detect OTPs from verification emails with full attachment support.

SMTP Sandbox

Drop-in SMTP replacement for Supabase Auth and other providers. Emails are captured for testing and never delivered to real recipients.

API & Webhooks

Query emails programmatically via REST API. Get notified instantly when emails arrive with signed webhooks.

Developer Experience

Ready for your codebase

Integrate with your favorite testing frameworks like Playwright, Cypress, or Selenium in minutes. Our SDK makes it trivial to verify email delivery.

Zero Spam Risk

None of the emails sent to our sandbox ever leave the system. Test safely with real user data.

Type-Safe SDK

Full TypeScript support with our official Node.js SDK.

example.ts

import { SigninID } from 'signinid';

// Set SIGNINID_SECRET_KEY environment variable
const client = new SigninID();

// Wait for a new verification email to arrive
const email = await client.inbox.waitForNew({
  to: 'user@test.com'
});

// Extract the OTP
if (email) {
  console.log('Verification code:', email.detected_otp);
}

Trusted Platform

1,000,000+

Registered email addresses

20,000,000+

Emails processed

Ready to streamline your testing?