The Mutual TLS security scheme in OpenAPI

Mutual TLS (mTLS) is a security protocol that enhances the security of API communication by requiring both the client and server to authenticate each other using digital certificates. This two-way authentication ensures that only trusted parties can establish a connection, providing an additional layer of security.

OpenAPI lets you define a Mutual TLS security scheme using the mutualTLS type.

Defining a Mutual TLS security scheme

Define a Mutual TLS security scheme in OpenAPI using the following structure:

components:
  securitySchemes:
    MutualTLS:
      type: mutualTLS
      description: Mutual TLS authentication for secure API communication.

The mutualTLS type requires no additional fields, as its primary purpose is to indicate that the API requires mutual TLS authentication. However, you can use the description field to provide API users with additional information about how to obtain a certificate.

components:
  securitySchemes:
    MutualTLS:
      type: mutualTLS
      description: >
        To access this API, you must provide a valid client certificate. 
        Please submit a request to the [infrastructure team](https://example.com) with 
        full information about what this application is to obtain a certificate.

Learn more about mutual TLS in the OpenAPI Specification  or the Cloudflare Learning Center .