ojsama

ojsama is an open-source JavaScript library designed to work with osu! beatmap data. It provides utilities to parse .osu beatmap files and extract timing, object, and metadata information, and to calculate a map’s difficulty rating, commonly referred to as star rating, using osu! standard difficulty models. The library is written in JavaScript and runs in both Node.js environments and in browsers via bundlers, enabling its use in serverside tooling as well as client-side applications.

Developed to support automated beatmap processing and tooling, ojsama is widely used in community projects for tasks such as beatmap analysis and the generation of difficulty estimates. It emphasizes a lightweight, dependency-minimal approach while aiming for accurate representation of beatmap difficulty.

Typical usage involves reading a beatmap file or content, constructing an osu beatmap object, and invoking the difficulty calculation to obtain the star rating and related statistics. The API focuses on exposing parsed beatmap data and a mechanism to compute difficulty metrics, making it useful for developers building osu! tooling, data analytics, or educational projects that explore beatmap structure.

ojsama is distributed as an open-source project, with its source code hosted on a public repository and available as an npm package. It benefits from community contributions and documentation that describes the API, provides examples, and outlines known limitations. As a tool in the osu! ecosystem, ojsama is cited by developers seeking a programmatic way to parse beatmaps and assess their difficulty in JavaScript environments.