This is a slack based application which can be used to schedule messages between a combination of different channels, users or groups irrespective of the timezone.
Run npm install to install dependencies and you have to set the SLACK_BOT_TOKEN, SLACK_APP_TOKEN, SLACK_SIGNING_SECRET as env variables as it is used inside the application.
After that you can run the application by node app.js
Search for Scheduler in the global shortcut
Type in the message and select the channels/groups/users as receivers
Select Date, Time and Timezone for sending the message.
Click on Submit.