From the project website (accessed 2019-10-31):
The Bibliotheca Teubneriana Latina Online (BTL) database provides electronic access to all editions of Latin texts published in the Bibliotheca Teubneriana, ranging from antiquity and late antiquity to medieval and neo-Latin texts. A total of approximately 13 million word forms are thus accessible electronically. The user interface allows various and differentiated searches. Classical scholars and ancient historians are provided with a valuable tool for both research and the preparation of teaching at school and university level. Each year, the database is extended by the texts of the newly printed Latin editions of the Bibliotheca Teubneriana.