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 following diagram demonstrates an application running on the Fitbit device, communicating with it's associated companion on the mobile device, which provides access to resources on the internet.

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


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 and Device API provide Outbox and Inbox queues to send and receive files.

Read the File-Transfer Guide for further information.