The 2.5 version of All-in-One Messenger for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The application lies within Communication Tools, more precisely Texting & Video calls. The actual developer of this free Mac application is Henrik Wenz. We recommend checking the downloaded files with any free antivirus.
From the developer:
All-in-One Messenger gathers messengers like WhatsApp, Telegram, Messenger, Skype and many more in one app. The program supports more than 40 messengers. All-in-One Messenger shows an unread message count right in your app bar and informs you via Desktop Notifications.
You may want to check out more Mac applications, such as Go for Messenger: Voice & Text Message Chat, Interaction Messenger or Enterprise Messenger, which might be similar to All-in-One Messenger.
Instant messaging
Instant messaging