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Email & SMS Passcodes

Easily sign-up and verify an account in one-step with one-time passcodes. Or use them in your sign-in flow for a secure passwordless experience.

What does OTP mean?

OTP stands for One-Time Passcode. It is a random, single-use, 6 digit code used to verify a user's identity. Best-practices for generating and verifying passcodes are defined by NIST 800-63B.

What is OTP authentication?

To be used for authentication, one-time passcodes can be sent to a user by SMS or email. If the user can verify the code they were sent, it means they control the email address or phone number where it was delivered.

Benefits of one-time passcodes

Seamless user experience

One-time passcodes are often more secure than static passwords, but context switching between applications can be annoying for end users. Clerk enables auto-fill for SMS one-time passcodes, creating a seamless and secure mobile authentication flow.

Deliverability you can count on

Stop worrying about complex configurations and multi-level dependencies with email and SMS providers. Clerk ensures speedy delivery of SMS & email passcodes.

Flexible implementation

Configuring and layering authentication methods is ridiculously easy with Clerk. SMS and email passcodes are no exception. They can easily be set as your primary authentication method for passwordless authentication, or layered on for a multifactor authentication, flow to strengthen security.

User verification and product security

Create a frictionless flow for your users, while increasing resistance to bots and suspicious accounts. One-time passcodes help users effortlessly create and verify an account in one step; while increasing the friction for bad actors.

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Learn more about our transparent per-user costs to estimate how much your company could save by implementing Clerk.