File Format Encyclopedia

Your resource for file format specifications.

Wotsup.org is a community-driven archive providing hundreds of file format specifications, hardware notes, and implementation guides. Browse and contribute to help keep legacy data accessible.

Start contributing How to use

• 810+ file formats
• 21+ categories
• Community maintained

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• How to use
• FAQ
• About

What's inside

A comprehensive format reference library.

Formats documented

810

Detailed specifications, diagrams, and implementation tips.

Categories covered

21

From graphics and audio to printers, CAD, and communications.

Specs archived

1134+

Reference files, whitepapers, and utility documentation.

Explore the collection

Search by extension or format name from any page (press /), or browse by category to find specs and decoding notes.

Browse all formats →

Engineering ready

Entries focus on structures, fields, and practical tips for building parsers.

Developer guidance →

Community powered

Submit corrections or new specs via GitHub. Every contribution is reviewed.

Contributing guide →

Get involved

Help expand the documentation.

Contribute format specifications, add implementation notes, or improve existing documentation. All contributions are welcome via GitHub.

• Submit specs via GitHub
• Add decoding tips
• Improve metadata + tagging

New to the archive?

Start with the quick guides.

Learn how to navigate the archive and find the format information you need.

How to use Wotsup.org Frequently asked questions Contact + feedback

Recent additions

Latest updates to the catalog.

1. Oct 6, 2026

   .7z updated 7Zip LZMA Compression SDK

   .aws updated AWSTAPE virtual tape drive Utilities and information

   .bmp updated Windows Bitmap (BMP/DIB)

   .bsp updated Quake 2 BSP File Format

   .c3d updated Biomechanical data file format

   .cmp updated FutureVision Audio File Formats (.CMP, .FST, .DAT)

   .coff updated DJGPP Common Object File Format Specification

   .css updated Cascading Style Sheets 1

   .dbf updated dBASE .DBF File Structure

   .edf updated European Data Format

   +17 more

2. Sep 30, 2026

   .asc added ASCII-armored OpenPGP data

   .gpg added OpenPGP binary data (GnuPG)

3. Sep 29, 2026

   .pfx added Personal Information Exchange (PFX / PKCS #12)

   .p12 added PKCS #12 personal information exchange

   .cer added X.509 certificate (.cer)

4. Sep 28, 2026

   .crt added X.509 certificate (.crt)

   .pem added PEM textual encoding

5. Sep 27, 2026

   .pyc added Python compiled bytecode

   .class added Java class file

   .dylib added Mach-O dynamic library

   .so added Shared object (ELF dynamic library)

Ready to contribute?

Every contribution helps keep file format knowledge accessible. Fork the repo, add your notes, and submit a pull request.

View the repository Contribution guide

Built on the foundation of Wotsit.org, originally created by Paul Oliver and contributors worldwide. Thanks to their pioneering work in documenting file formats. Read more about Wotsup.org →