Stop Gluing Auth0 to SendGrid

If you're running a SaaS product, there's a good chance your stack looks something like this:

• Auth0 for user authentication
• SendGrid for transactional email
• Custom code connecting the two

That custom code — the Auth0 Actions, the webhook handlers, the queue consumers — is what we call "glue code." And it's a maintenance burden that compounds over time.

The glue code problem

Every auth event that needs an email requires integration code:

1. User registration → Send welcome email via SendGrid
2. Email verification → Send verification link via SendGrid
3. Password reset → Send reset link via SendGrid
4. MFA enrollment → Send setup instructions via SendGrid
5. Suspicious login → Send security alert via SendGrid

For each of these, you need:

• An Auth0 Action or Rule that fires on the event
• A SendGrid API call with the right template
• Error handling (what if SendGrid is down?)
• Retry logic (what if the email fails?)
• Logging and monitoring
• Template management in a separate dashboard

That's 200-500 lines of integration code, spread across Auth0 Actions, your backend, and possibly a message queue. And every time you add a new auth flow, you add more glue.

The real cost

Glue code isn't just annoying — it's expensive:

• Development time: Building and testing integrations takes days, not hours
• Maintenance burden: When Auth0 changes their Action API or SendGrid updates their SDK, your glue code breaks
• Debugging complexity: When a user says "I never got my verification email," you have to trace through two systems
• Vendor lock-in: Your integration is specific to Auth0 AND SendGrid — switching either one means rewriting the glue

What a unified platform looks like

With Zyphr, auth and email are the same platform:

// User signs up
const { user } = await zyphr.auth.register({
  email: 'jane@example.com',
  password: 's3cur3P@ss',
});

// Done. Zyphr automatically sends the verification email.
// No glue code. No webhook handler. No queue consumer.

When auth events happen, the corresponding emails go out automatically:

The math

Let's compare costs for a typical SaaS with 25,000 monthly active users and 100,000 transactional emails:

The direct vendor savings are significant, but the real win is eliminating the engineering time spent maintaining integration code.

When to stay with Auth0 + SendGrid

Be honest about your needs:

• Enterprise SSO: If you need SAML, AD/LDAP, or custom database connections, Auth0 has more mature enterprise features
• Marketing email: If you need bulk email campaigns, SendGrid handles both transactional and marketing
• Deep investment: If you've built extensive Auth0 Actions with complex business logic, migration has a real cost

When to switch

• You're starting a new project and want to avoid vendor sprawl from day one
• Your glue code has become a maintenance burden
• You're paying for two services that could be one
• You want auth events to trigger emails without writing integration code

Making the switch

Migration is straightforward:

1. Export users from Auth0 (passwords transfer as bcrypt hashes)
2. Import SendGrid templates (Zyphr uses Handlebars too)
3. Replace two SDKs with one
4. Delete your glue code

Most teams complete the migration in under a day.

See the full comparison →