Construct is now developed on https://github.com/construct/construct

Construct is a powerful declarative parser for binary data.

It is based on the concept of defining data structures in a declarative manner, rather than procedural code: Simple constructs can be combined hierarchically to form increasingly complex data structures. It's the first library that makes parsing fun, instead of the usual headache it is today.

Construct features bit and byte granularity, symmetrical operation (parsing and building), component-oriented declarative design, easy debugging and testing, an easy-to-extend subclass system, and lots of primitive constructs to make your work easier:

• Fields
• Structs
• Unions
• Repeaters
• Meta constructs
• Switches
• On-demand parsing
• Pointers
• And more!

Construct should run on any Python 2.5+ implementation. It has no external dependencies.