Windows
Open https://api.securityhive.io/v1/blockpages/rootca to download the SecurityHiveCA.crt file.
Open the SecurityHiveCA.crt file (the Certificate window will open).
Click on Install Certificate.
In the Certificate Import Wizard, when prompted for the Certificate Store, choose Place all certificates in the following store and select the Trusted Root Certification Authorities store.
macOS
Open https://api.securityhive.io/v1/blockpages/rootca to download the SecurityHiveCA.crt file.
Open the SecurityHiveCA.crt file (the Keychain Access.app will open with the list of Certificates installed on your computer).
Double-click on SecurityHive Root CA in that list.
Under Trust, choose Always Trust for Secure Socket Layers (SSL).
Close the window (you may be asked to enter your system password to confirm the change).
iOS
Open https://api.securityhive.io/v1/blockpages/rootca, then choose Allow.
Open the Settings app, then go to General → Profiles.
Open SecurityHive Root CA, then Install.
In the Settings app, go to General → About → Certificate Trust Settings.
Enable Full Trust for SecurityHive Root CA.
Android
Open https://api.securityhive.io/v1/blockpages/rootca, then choose Download.
Open the downloaded SecurityHiveCA.crt file.
When asked, name the certificate SecurityHive.
Firefox
Open https://api.securityhive.io/v1/blockpages/rootca to download the SecurityHiveCA.crt file.
Open about:preferences →Privacy & Security.
Scroll down to Certificates and click View Certificates…
In the Authorities tab click Import.
Select the NextDNS.cer file.
Check Trust this CA to identify websites then click OK
Chrome, Chromium
Open https://api.securityhive.io/v1/blockpages/rootca to download the SecurityHiveCA.crt file.
Open chrome://settings/certificates
In the Authorities tab click Import.
In the lower right, select All Files
Select the SecurityHiveCA.crt file.
Check Trust this certificate for identifying websites then click OK.
If you're using Firefox, an additional step is required:
Enter about:config in the address bar, then press Enter.
If asked, click on Accept the Risk and Continue.
Set the value for security.enterprise_roots.enabled to true.