1. AssetStudio (Best for Decompiling and Inspecting AssetBundles)
Most developers searching for a "Unity3D file viewer" actually want to explore (bundles) or raw asset files without opening the editor. unity3d file viewer
UABEA is a powerful, cross-platform tool used to modify and view Unity asset bundles. While it is slightly more technical than AssetStudio, it offers deeper inspection capabilities. it offers deeper inspection capabilities.