The Talmudic commentary called Tosafoth has been printed together with the Talmud text itself for many centuries. For example, even Maharal testifies (in 1595) to this in Nesiv Hatorah ch. 5:
והכל בשביל שלמודם תוס' דבר שהוא הוספה וכי לא היה טוב יותר שיקנה גוף התלמוד קודם, והכל בשביל שנדפסו התוספות אצל הגמרא. ...It is because they were taught Tosafoth, which, as its name attests, is only but an addition. However, would it not have been more fitting for a student to study the very text of the Talmud itself? This is only because the Tosafoth are printed on the same page as the Talmud.
However, I imagine that prior to such printing presses they were copied as a stand alone work. Regardless, as with many books, such as Tosefta, has there been a printing of the Tosafoth as a stand alone book? Besides reference, they could also serve as critical version of the texts.
Although there are many different volumes in print which contain in the title ‘Tosafoth’, I seek only that which is printed in the standard Talmud layout.