Out of interest: does anyone know what those three Safari extensions are on Jeff's screenshots?
Edit: thx for answers below!
The </> looking icon is the Userscripts extension[1]. The one in the middle is for 1Password. The RSS looking icon I'm not sure about.
Maybe Subscribe with Reeder[0], 1Password[1], Userscripts[2]. The RSS and HTML icons are obviously fairly generic, so not 100% sure.
[0]: https://reederapp.com
[1]: https://1password.com
[2]: https://github.com/quoid/userscripts