WhatsOpenMe is a great tool for your favourite messenger app to send messages to any numbers those are not saved in your contacts.
How it works?
1. Enter a number to which you are going to send message OR select numbers from recent calls or Message.
2. Type your text message and tap on send button.
3. This will take you to the your favourite messenger then a chat window is created with given number.

How to send Multimedia Messages?
1. Enter a number or select from recent call logs to which you are going to send message.
2. Tap on 'Send Media'.
3. You will be directed to your favourite messenger official app then you can attach any media from there.


Note - WhatsOpenMe is using official public API available from your favourite messenger app.