Hostetter is the proprietor of the journals Vinyar Tengwar and Tengwestië, which assess Tolkien's linguistic material. He is a frequent contributor to the mailing-lists Tolklang and Elfling, and founded another in 2002, Lambengolmor. With Christopher Gilson, Arden Smith, Bill Welden, and Patrick Wynne, Hostetter was commissioned by Christopher Tolkien to gather and organize J.R.R. Tolkien's writings of his own languages for publication, resulting in volumes 11 - 17 of the journal Parma Eldalamberon, and continuing in Vinyar Tengwar.
Hostetter compiled with scholar Verlyn Flieger Tolkien's Legendarium: Essays on The History of Middle-earth, published in 2000. In 2017 he provided an opening essay, "Inventing Elvish", to the Bodleian Library's book Tolkien: Maker of Middle-earth.