ASSET File

What are ASSET files and how to open them

Are you having problems opening an ASSET file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your ASSET files.

What is an ASSET file?

An .ASSET file is an Unity YAML Scene file.

Unity YAML Scene files serve to store the contents of a Unity scene, e.g. all the GameObjects, their Components, hierarchy, settings (such as lighting, fog, rendering, etc.), in human-readable serialized text form. Unity itself generates these files when the project's Asset Serialization Mode is set to "Force Text," otherwise scenes are stored in a binary format. Scenes represent the layout for a level, menu, or any interactive environment in a Unity project.

The contents are written in a custom subset of YAML (YAML Ain't Markup Language), meaning much of the structure resembles YAML but some features are unsupported or modified. Each object - such as GameObjects, Components, scene-wide settings - is serialized as its own YAML document within the file. Documents are introduced by the sequence ---, and each begins with a header giving a Class ID and a File ID. Properties inside objects are stored as mappings (key/value pairs), with nested values for components. Unity also includes headers at the start of the file to declare the YAML version and tag definitions; missing data may be filled in with default values on import.

Files produced in this format typically go through Unity's build or editor workflow - Unity writes them when scenes are saved or updated, and the Unity Editor reads them back to reconstruct the scene in memory. They are part of the project assets, versioned alongside scripts and other asset types. During player builds, scene data may be transformed: assets referenced by scenes get grouped into separate "shared assets" files, object IDs and layout may be optimized or reorganized, especially to reduce duplication or satisfy platform constraints.

A signature at the very start of these files includes the ASCII string %YAML 1.1 followed by %TAG !u! tag:unity3d.com,2011: and then the first document marker ---!u!. That identifies the file as a Unity YAML scene: it must begin with that two-line header (version and tag), followed by one or more documents each starting with --- !u!{ClassID} &{FileID}.

How to open ASSET files

Important: Different programs may use files with the ASSET file extension for different purposes, so unless you are sure which format your ASSET file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 22, 2026

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