ASDF File

What are ASDF files and how to open them

Are you having problems opening an ASDF 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 ASDF files.

What is an ASDF file?

An .ASDF file is an Advanced Scientific Data Format file.

Advanced Scientific Data Format files store scientific data with rich, hierarchical metadata and efficient binary arrays. They are created by tools that implement the ASDF specification, especially the ASDF library (notably the reference Python package). These files allow scientists to combine human-readable metadata and large binary data in a single, self-describing format that supports data validation, compression, and extensibility.

Metadata is written in YAML, allowing nested data types like dictionaries, lists, strings, numbers, unit metadata and mappings. Binary data blocks store large numerical arrays and can be memory-mapped or compressed using algorithms such as zlib, bz2, lz4. The format uses JSON Schema for validating content (structure and expected data types), versioning to ensure backward compatibility, optional schema extensions, and a clear separation between metadata and binary payloads.

These files begin with the ASCII characters "#ASDF" at offset 0, which serves as a magic header identifying the format.

How to open ASDF files

Important: Different programs may use files with the ASDF file extension for different purposes, so unless you are sure which format your ASDF 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 21, 2026

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