<commit_before>---
description: Learn how to create a code verifier while implementing the mobile login flow.
toc: false
topics:
  - api-authentication
  - oidc
  - authorization-code
  - pkce
  - mobile-login-flow
contentType: tutorial
useCase:
  - secure-api
  - call-api
  - add-login
---

# Create a Code Verifier

Create a `code_verifier`, which is a cryptographically-random key that, along with its transformed value (called the `code_challenge`), will be sent to Auth0 to request an `authorization_code`.

<div class="code-picker">
  <div class="languages-bar"><commit_msg>Update create-code-verifier.md<commit_after>---
description: Learn how to create a code verifier while implementing the mobile login flow.
toc: false
topics:
  - api-authentication
  - oidc
  - authorization-code
  - pkce
  - mobile-login-flow
contentType: tutorial
useCase:
  - secure-api
  - call-api
  - add-login
---

# Create a Code Verifier

Create a `code_verifier`, which is a cryptographically-random key that will eventually be sent to Auth0 to request an `authorization_code`.

<div class="code-picker">
  <div class="languages-bar">
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