TFST file format is developed by Tansee.com for storing SMS, MMS, iMessage and WhatsApp message data from iPhones, iPads, or iPod Touch devices on a Mac.
The TFST file, which has the file extension '.tfst', can be opened using Tansee iPhone Message Transfer for Mac. You can either double-click on the .tfst file or open Tansee iPhone Message Transfer for Mac, then go to File > Open tfst file.
Here is a step-by-step guide on how to transfer SMS, MMS, iMessage and Whatsapp data from your iPhone, iPod, or iPad to your Mac.