Walkie - Walkie is an online communication providing software that allows you to remain in touch with the other persons.
WhatsMany - Send personalised WhatsApp messages in bulk
Cord - One tap voice chat
LoopMessage - LoopMessage is a perfect macOS tool for personalized mass messaging via iMessage/SMS, WhatsApp, Facebook Messenger, Telegram, Viber, and Skype.
Slack Voice Chat by Standuply - Easily record and send voice messages on Slack 🗣️
Porterhouse - Send mass iMessage and SMS texts from your existing number with a single click!