This test browser was released in March 2016, and the features used on Safari’s technology preview may be actually added to the feature Safari.
A few days ago, Apple pushed an update for Safari’s technology preview, and the browser itself was released in March this year. The features used on the technology preview may be actually added to the feature Safari.
This has been the 19th version, which include the update and bug fixing for HTML format validation, pointer lock API, item import, URL analysis program, web page checker, Shadow DOM, render, etc. Addionally, Webkit and TouchBar have been available now.
The purpose that Apple released the technology preview is to collect feedback from developers and users. Safari Technology Preview and the current Safari are compossible. Because it supports iCloud, all your latest favorites, bookmarks and reading lists on the current Safari will be synced to the Technology Preview. Common users are allowed to download it without developer accounts.