Communications Guide
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Communications Guide


In the communication guide we demonstrate how application developers can utilize the Device API on the Fitbit device, and Companion API on the mobile device, to send and receive data, and transfer files.

The Fitbit mobile application is used as an intermediary for all communications, and it also acts as a gateway to internet resources.


Messaging is bi-directional, but File Transfers can only be sent from the companion to the device at this time.


The Messaging API provides a synchronous socket based communications channel for sending and receiving simple messages while the app is running on the device.

This API has an identical implementation in the Device API and the Companion API, and should feel very familiar to developers who are experienced with the WebSocket API.

Read the Messaging Guide for further information.

File Transfer

The File-Transfer API provides an asynchronous mechanism for sending binary or text files from the companion, and receiving them on the device, even if the app is not currently running on the device.

The Companion API provides an Outbox queue for file transfers, and the Device API provides a simple Inbox to receive the files.

Read the File-Transfer Guide for further information.