WhatsMany - Send personalised WhatsApp messages in bulk
Twitter DMs Library - Collection of the best Twitter DMs on the Planet
LoopMessage - LoopMessage is a perfect macOS tool for personalized mass messaging via iMessage/SMS, WhatsApp, Facebook Messenger, Telegram, Viber, and Skype.
Sidebird - Notion to Twitter thread.
Porterhouse - Send mass iMessage and SMS texts from your existing number with a single click!
Twidd - Enhanced Twitter DMs - Create and use DM templates, all within a browser extension.