Bible Study Aid is a free educational app developed by Thunderstone Apps for Jehovah's Witnesses. The app allows users to download and open various media publications from the JW.ORG website, including PDFs, EPUBs, RTFs, MP3s, and MP4s. The app also offers access to the New World Translation of the Holy Scriptures in 112 languages, Examining the Scriptures Daily 2019 in 222 languages, magazines in 491 languages, meeting workbooks in 379 languages, and books and brochures in 779 languages.

The app is a useful tool for Jehovah's Witnesses who want to study and access various publications on their mobile devices. With a user-friendly interface and access to a wide range of publications in multiple languages, Bible Study Aid is an excellent resource for anyone looking to learn more about the teachings of Jehovah's Witnesses.