The Indonesian Music Museum stores various music collections in the form of cassettes, compact discs, vinyl records, and music-related books. This self-managed museum has the potential to become an institution that stores musical works from various countries. Management has been carried out properly, starting from inventory of collections to registration, but still manually. The implementation of the Senayan Library Management System (SLiMS), which is an open source based application, is one solution for managing collections more quickly and making it possible to access them remotely. The method used in this research is a qualitative study using observations and interviews so that it can produce an appropriate management system for the museum. The main informants are museum managers who are considered to understand the metadata needs of their museum collections. All results of observations and interviews are used as guidelines in determining any changes to the applications used to manage collections at the Indonesian Music Museum. This research produces an open source application-based museum collection inventory system. Several changes and adjustments were made to this application so that it could be implemented in the museum. Terms referring to library collections were changed and adapted to the use of terms relevant to music collections. The grouping of collections based on music genres and artists' regions of origin which is usually carried out by the museum is still maintained to become the characteristic of this museum itself. The Indonesian Music Museum can implement this application in a sustainable and long-term manner. Using this system helps the museum to obtain data records of collections and their movements, as well as inventory data on collections currently owned.