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The longer answer…Fitbit has confirmed that users will not be disconnected from any 3rd part party sources when moving to a Google account. The Validic Marketplace does not require any changes and all existing Fitbit user tokens will remain valid. There is no action required for you or your users related to the migration.
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As part of the process to move a user from Fitbit to Google, the Fitbit app presents users with a screen that shows them all of their current 3rd party app connects connections along with the ability to disconnect any they want.
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