As a result, the FiddlerRootCertificate.crt file will be created in the Desktop folder. Use the Export root certificate(DER/Binary format) option from the drop-down menu. Open Fiddler Everywhere and go to Settings > HTTPS_ and expand the Advanced Settings menu. If the automatic installation and enabling of the trust certificate do not work, you can manually install the trust certificate to your keychain: For the step-by-step guide, refer to the First Steps with Fiddler Everywhere on macOS article. It is recommended that you install the Fiddler Everywhere root certificate on macOS automatically. How can I install the trust certificate automatically or manually? Solution To capture secure traffic (HTTPS), Fiddler Everywhere needs to install a root trust certificate, called DO_NOT_TRUST_FiddlerRoot, in the Keychain Access application.

Manually Installing the Root Certificate on macOS Environment