> For the complete documentation index, see [llms.txt](https://help.cymmetri.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.cymmetri.io/single-sign-on/passwordless/otp-based.md).

# OTP Based

A one-time password (OTP) is an identity verification tool for authenticating users logging into an account, network, or system. A user is sent a password containing a unique string of numbers or letters that can only be used once to log in. Used or not, these password codes expire after a short period of time.

In Cymmetri, if OTP is enabled for passwordless login, the user is prompted for an OTP which is sent to the user's registered mobile number and email address during login.![](/files/03FzD689BLKbMw2hUVGJ)

After OTP verification, the user is verified and logged in into the system


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