Microsoft Edge has extensions now

Well, presently only in the latest Windows 10 Insider Preview (build 14291).

However, in due course, it will be released to the mainstream (that's you and me) Windows 10 users. When released for the mainstream you just go to Windows Store and download.

This is testing time for the insiders. This is the time to test it out so that when it is out of the door there are no surprises.

What are the extensions available for the insiders?

They are all listed and explalined here:
https://developer.microsoft.com/en-us/microsoft-edge/extensions/

The Microsoft Translator
Supports more than 50+ languages.
Languages that are supported by this extension:
   # Arabic
   # Bosnian (Latin)
   # Bulgarian
   # Catalan
   # Chinese Simplified
   # Chinese Traditional
   # Croatian
   # Czech
   # Danish
   # Dutch
   # English
   # Estonian
   # Finnish
   # French
   # German
   # Greek
   # Haitian Creole
   # Hebrew
   # Hindi
   # Hmong Daw
   # Hungarian
   # Indonesian
   # Italian
   # Japanese
   # Kiswahili
   # Klingon
   # Klingon (plqaD)
   # Korean
   # Latvian
   # Lithuanian
   # Malay
   # Maltese
   # Norwegian
   # Persian
   # Polish
   # Portuguese
   # Queretaro Otomi
   # Romanian
   # Russian
   # Serbian (Cyrillic)
   # Serbian (Latin)
   # Slovak
   # Slovenian
   # Spanish
   # Swedish
   # Thai
   # Turkish
   # Ukrainian
   # Urdu
   # Vietnamese
   # Welsh
   # Yucatec Maya

What a terrible world! Microsoft has a translator for Klingon but not for Telugu and Kannada spoken by millions!

The other extensions are presently:
Redit enhancement suite

Mouse gestures

Here is a video about installing extensions :