The author created a web-based music player called Underscore to solve the problem of choosing music while working. Underscore allows users to input music links from various platforms such as Spotify, YouTube, and Bandcamp. Reloading the page selects a random piece of music from the user's collection. The application features a simple interface to manage and organize music resources. There is no automatic playlist syncing or API integration for simplicity. The music plays through embedded players, requiring user interaction to start some tracks. Despite its manual nature, the author loves using it with their large music library. The app includes a background animation and a unique visual display for media embeds. The author has opened the app to kottke.org members to create their own collection. Non-members can still explore the author's collection. The author considers Underscore best-suited for longer musical selections.