Support for the legacy Fitbit Web API ends on September 30, 2026
Important: Support for the legacy Fitbit Web API ends on September 30, 2026. After this date the API will continue to operate, but Google will no longer fix bugs or provide API support. On October 30, 2026, the Fitbit Web API will be turned off and will no longer function or sync data to or from Fitbit users. To continue accessing data for your users after this date, migrate to the Google Health API.
Communications Guide
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Communications Guide

Overview

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.

Messaging

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.