About File Extension Lookup & Magic Bytes Directory
Universal file extension and file format technical directory. Search across document, media, archive, code, database, and system extensions to look up official format names, associated MIME types, developing organizations, default software applications, and file magic byte signature headers.
Key Capabilities & Features
- Extensive database of 300+ file extensions across documents, media, code, and archives
- Lists file magic bytes (header signatures) for low-level file format verification
- Includes associated MIME types and official developer organizations (Adobe, Microsoft, W3C, ISO)
- Recommends standard open-source and native software to open each format
- Filterable by file category (Document, Image, Audio, Video, Code, Archive, Database)
How to Use File Extension Lookup & Magic Bytes Directory
Search Extension
Type an extension like .pdf, docx, wasm, or tar.
Filter by File Type
Select Document, Image, Media, Code, or Archive.
Inspect Magic Bytes
Review the hexadecimal magic byte signature used for file type detection.
Find Opening Software
Check recommended applications to open or convert the file.
Privacy & In-Browser Execution Guarantee
100% Client-Side. File extension lookups execute locally in your browser with zero data collection.
Frequently Asked Questions
What are magic bytes in a file?
Magic bytes are a unique sequence of hexadecimal bytes located at the very beginning of a file (the header) that uniquely identify the file format, regardless of what file extension is displayed in the filename.
Can an extension be changed without corrupting the file?
Changing an extension simply changes how the operating system associates the file with an application; it does not change the internal data format. However, incompatible programs may fail to open it.