osu preview is a Firefox extension designed for osu! enthusiasts, allowing users to preview the gameplay of beatmaps without the need to download them. It supports the majority of osu! standard and osu! mania maps, although compatibility may vary with older maps. This feature is particularly useful for players who want to assess a map's playability before committing to a download.

The extension enhances the preview experience by providing synchronized audio playback that aligns with hit objects in the map. Users can also seek to any point in the map, making it easy to find specific sections or challenging parts of the beatmap. With its subscription-based access, osu preview is a valuable tool for anyone looking to improve their osu! gameplay.