Official app for OS X from Telegram team
This software is available under GPL v3 license.
Source code is available on GitHub.

Version history

v 0.8 stable 26.03.15

  • Add a comment before forwarded messages
  • Hashtags suggestions in new message and search fields (based on recent searches)
  • Button to jump back to a reply after viewing the original message
  • Add people to groups by username

v 0.7.26 dev 26.03.15

  • Some bugfixes

v 0.7.25 dev 25.03.15

  • Add people to groups by username
  • Copy @username from profile context menu

v 0.7.24 dev 24.03.15

  • Forward messages with comment or sticker before them
  • Recent hashtags autocomplete in message and search fields
  • Move from reply to original message and back

v 0.7.23 stable 20.03.15

  • Reply to specific messages in groups
  • Mention @usernames in groups to notify multiple users

v 0.7.22 dev 20.03.15

  • Critical bug in messages delivery fixed

v 0.7.21 dev 19.03.15

  • Reply to specific messages in groups
  • Mention @usernames in groups to notify multiple users

v 0.7.20 stable 13.03.15

  • Lock your app with a passcode

Dev version

If you would like to get all updates faster and be the first to test new features, you are welcome to use Telegram Desktop's dev version instead of the public one.

The public version is updated less frequently, but is more stable than the dev version.

Here are the dev version links for different platforms:

Windows Setup
Windows Portable
Mac OS X Setup
Linux 64 bit
Linux 32 bit

Just install it on top of your current Telegram Desktop and there you go.
Your feedback is welcome on Twitter