Push notification file(Header + payload) size limit for different mobile OS What is the maximum size of Notification message that can be sent to the devices.I searched many places regarding this question but i couldnt find the answer.

For Android the message payload is upto 4 KB but for IOS u can able to send only 256 bytes of data. 

The maximum size of a notification for windows 7 is 1 KB for the header and 3 KB for the payload. Notifications exceeding these limits will be discarded and a WebException with a status of WebExceptionStatus.ProtocolError will be raised.

Hi i see that already answer has been provided for android, ios and windows phone. The value for BlackBerry is 8KB(payload, header and images). You can get more knowledge on pushnotification in given link
https://developer.blackberry.com/html5/apis/beta/blackberry.push.pushservice.html