Making your own Safari Extension

Case 1

https://developer.apple.com/library/content/documentation/Tools/Conceptual/SafariExtensionGuide/UsingExtensionBuilder/UsingExtensionBuilder.html

Case 2

Introduction

https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/SafariAppExtension_PG/

Creating and Running Your First Safari App Extension

https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/SafariAppExtension_PG/CreatingandTestingYourFirstSafariAppExtension.html

Injecting a Script into a Page

https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/SafariAppExtension_PG/AddingScriptContent.html#//apple_ref/doc/uid/TP40017319-CH7-SW1

Adding a Toolbar Item

https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/SafariAppExtension_PG/AddingaToolbar.html#//apple_ref/doc/uid/TP40017319-CH9-SW1

Access and Permissions

https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/SafariAppExtension_PG/DeterminingWhichPagesanExtensionCanAccess.html#//apple_ref/doc/uid/TP40017319-CH10-SW1