Activegram PRO Messenger is an unofficial messenger that uses Telegram's API with advanced features. The app is available for Android users and is completely free.

One of the unique features of Activegram is its Ghost mode which allows users to hide their online status and read messages without being seen. The app also has a feature to manage hidden chats, radar friends, check profiles, lock chats, view edited messages, and make personalized stickers.

Activegram also offers some additional features such as using different fonts, customizing templates, managing files and downloads, and managing auto answers. The app also has a Sticker confirmation before Sent feature, a main server of DC-VPN, and a Channel Helper for special channel owners.

Security-wise, Activegram is on par with Telegram, and no messages are visible to the developers. Overall, Activegram PRO Messenger is a great alternative to Telegram with some added features that make messaging more fun and convenient.