Apple has had an Extensions Gallery for Safari, a place where you could discover and download 3rd party extensions for your browser. With the recent launch of Safari 9.0 along with OS X El Capitan, Apple has now moved the Extensions Gallery to a new place and URL. The Safari Extensions Gallery is now available at https://safari-extensions.apple.com and with Version 9.0, Apple has changed the way Safari Extensions are built, distributed and updated. A brief summary of the changes is that:
1. To be able to build and distribute Safari Extensions, you now have to sign up for the Apple Developer Program, which costs $99/year. Previously, you could develop and self-sign your own Safari Extensions. That is no longer possible.
2. Apple now hosts and serves Safari Extensions directly from the above linked Extensions Gallery. The extensions are neatly categorized and are manually approved by Apple. You can download and install the extensions with a single click.
3. Only those Safari Extensions that are downloaded directly from Apple can be updated automatically. This means that the extensions you have downloaded from 3rd-party website, or a developer’s own website, will **not auto-update**. Developers can still sign their own extensions and make them available for download, but users will have no way to updating them.