Hợp Âm Chuẩn - Guitar Tabs is a free Vietnamese music app that provides chord charts for guitar, ukulele, and piano players. Developed by Thien Nguyen and his team at hopamchuan.com, this app boasts the largest Vietnamese chord library, with an average of 5-10 new songs added daily.

One of the app's main features is its offline functionality, allowing users to access chord charts without an internet connection. Users can also update their library via WiFi or 3G. The app also includes helpful tools such as automatic scrolling, font size adjustment, and the ability to change the chord key. Additionally, users can manage and sync their playlists and favorites with their hopamchuan.com account.

The app's search function allows users to find chords by song, artist, or author. Each chord chart displays finger placements for all chord positions and lyrics for each song. The app also supports multiple instruments, including guitar, ukulele, and piano. With a user-friendly interface and regular updates, Hợp Âm Chuẩn - Guitar Tabs is a must-have for all Vietnamese musicians.