Data Synchronization Timing for Heart Rate Intraday Data via Fitbit Web API

[Tetsu_I]

We are developing an application using the Fitbit Web API, and we have the following question:

How long does it typically take for data after the lastSyncTime (obtained via the Device API) to be fully synchronized on the Fitbit servers?

We currently retrieve Heart Rate Intraday data via the Web API approximately 3 hours after obtaining the lastSyncTime. However, we have noticed that additional data sometimes becomes available when checking after a longer period. Could you please advise on how we can verify that the data has been completely synchronized on the server?

We understand that for Activity and Body data, the Subscription feature allows the client to receive data as soon as it is synchronized on the server. However, since Heart Rate data does not support Subscriptions, we would appreciate your guidance on the recommended method to confirm its full synchronization.

Thank you for your assistance.

[GordonFitbit · Accepted solution]

Hi @Tetsu_I 

You are correct that the Heart Rate endpoints do not support subscriptions.  If your application supports the activity scope, you can use the activity notification to know when to pull heart rate data.  My understanding is the heart rate data is available almost immediately after the data is synced to our servers.  If you're not seeing heart rate data, there could be a few reasons:

1. The device the user is recording data does not support heart rate, i.e. mobile track
2. The user is not wearing their tracker tight enough on their wrist
3. the first sync of the day contains a lot of data (sleep, calories, heart rate, HRV, etc) and might require multiple syncs before the data is available.

I'll make a note to update the documentation with this information.

[Tetsu_I]

Thank you for your detailed response. We appreciate the insight regarding the heart rate sync process and the suggestion to use activity notifications if the application supports the activity scope. We haven’t worked with subscriptions before, so we’ll definitely look into that option.

Regarding the scenario where multiple syncs might be necessary, is it correct to understand that using subscriptions will allow us to capture the data that is synchronized later?

Thank you again for your assistance.

[GordonFitbit]

You will receive a notification for every sync where data in that collection is updated.