# Kaitai Struct

> declarative binary data format specification language

**Wikidata**: [Q29053521](https://www.wikidata.org/wiki/Q29053521)  
**Source**: https://4ort.xyz/entity/kaitai-struct

## Summary
Kaitai Struct is a declarative programming language for specifying binary data formats, allowing users to define file structures in a human-readable YAML-based syntax. It enables automated parsing of complex binary formats into structured data, making it easier to work with proprietary or undocumented file formats.

## Key Facts
- **Declarative language**: Kaitai Struct is a type of programming language used to specify binary data formats.
- **Based on YAML**: The language uses YAML syntax for defining file structures.
- **File extension**: `.ksy` is the standard file extension for Kaitai Struct specifications.
- **First release**: Version 0.2 was released on April 6, 2016.
- **Latest stable version**: 0.11 (as of 2025).
- **Website**: Official site is [kaitai.io](https://kaitai.io/).
- **Twitter handle**: @kaitai_io (account created April 12, 2016).
- **Social media followers**: 1,594 (as of January 10, 2021).
- **File format identification pattern**: Files begin with the hexadecimal sequence `6D6574613A`.
- **Source code repository**: Hosted on GitHub at [kaitai-io/kaitai_struct](https://github.com/kaitai-io/kaitai_struct).

## FAQs
### Q: What is Kaitai Struct used for?
A: Kaitai Struct is used to define and parse binary file formats in a declarative way, allowing developers to work with complex data structures without manual coding.

### Q: How do I write a Kaitai Struct specification?
A: You write specifications in YAML format with a `.ksy` extension, defining the structure of the binary data using Kaitai Struct's syntax.

### Q: What programming languages does Kaitai Struct support?
A: Kaitai Struct supports multiple languages, including C++, C#, Go, Java, JavaScript, Lua, Perl, PHP, Python, Ruby, and Rust.

### Q: Where can I find documentation for Kaitai Struct?
A: Official documentation is available at [doc.kaitai.io](http://doc.kaitai.io/user_guide.html) and [doc.kaitai.io/ksy_reference.html](http://doc.kaitai.io/ksy_reference.html).

### Q: How do I get help with Kaitai Struct?
A: You can ask questions on Stack Overflow using the [kaitai-struct tag](https://stackoverflow.com/tags/kaitai-struct) or check the official documentation.

## Why It Matters
Kaitai Struct addresses the challenge of working with binary file formats, which are often proprietary, poorly documented, or complex. By providing a declarative language to define these formats, it simplifies the process of parsing and working with binary data. This tool is particularly valuable for reverse engineering, game modding, forensic analysis, and any scenario where structured access to binary data is needed. Its YAML-based syntax makes it accessible to developers who may not be experts in low-level binary parsing. The project has evolved significantly since its initial release, with regular updates and support for multiple programming languages, making it a versatile tool in the developer ecosystem.

## Notable For
- **Declarative approach**: Unlike traditional binary parsing, Kaitai Struct allows users to define file structures declaratively, reducing the need for manual coding.
- **Multi-language support**: It generates parsers in multiple programming languages, increasing its usability across different development environments.
- **Open-source**: The project is hosted on GitHub, fostering community contributions and transparency.
- **Active development**: Regular releases (as of 2025) indicate ongoing maintenance and improvement.
- **Documentation**: Comprehensive guides and references are available, making it accessible to both beginners and experts.

## Body
### Overview
Kaitai Struct is a declarative language for specifying binary data formats. It allows users to define file structures in a YAML-based syntax, which is then compiled into parsers for various programming languages. The language was first released in 2016 and has since undergone multiple updates, with version 0.11 being the latest stable release as of 2025.

### Technical Details
- **Syntax**: Kaitai Struct specifications are written in YAML and saved with the `.ksy` file extension.
- **Compilation**: The language compiler generates parsers in languages such as C++, C#, Go, Java, JavaScript, Lua, Perl, PHP, Python, Ruby, and Rust.
- **Identification**: Files using Kaitai Struct begin with the hexadecimal sequence `6D6574613A`.

### Community and Support
- **Social media**: The project has an active Twitter presence (@kaitai_io) with 1,594 followers as of January 10, 2021.
- **Documentation**: Official user guides and syntax references are available on the project's website.
- **Community engagement**: Users can seek help on Stack Overflow using the dedicated [kaitai-struct tag](https://stackoverflow.com/tags/kaitai-struct).

### Development History
- **Initial release**: Version 0.2 was released on April 6, 2016.
- **Latest release**: Version 0.11 was released on October 16, 2025, and is marked as the stable version.
- **Regular updates**: The project has seen multiple releases, with the most recent being version 0.10 on July 8, 2022.

### Use Cases
Kaitai Struct is used in various domains, including reverse engineering, game modding, and forensic analysis, where structured access to binary data is required. Its declarative nature simplifies the process of working with complex file formats.

## References

1. [Release 0.2. 2016](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.2)
2. [Release 0.3. 2016](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.3)
3. [Release 0.4. 2016](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.4)
4. [Release 0.5. 2016](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.5)
5. [Release 0.6. 2017](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.6)
6. [Release 0.7. 2017](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.7)
7. [Release 0.8. 2018](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.8)
8. [Release 0.9. 2020](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.9)
9. [Kaitai Struct v0.10 released. 2022](http://kaitai.io/news/2022/07/08/kaitai-struct-v0.10-released.html)
10. [Release 0.11. 2025](https://github.com/kaitai-io/kaitai_struct/releases/tag/0.11)
11. [TrID](https://mark0.net/soft-tridscan-e.html)