By Category

String and text processing

• Conversion: Polymorphic and lexical casts.
• Format: The format library provides a class for formatting arguments according to a format-string, as does printf, but with two major differences: format sends the arguments to an internal stream, and so is entirely type-safe and naturally supports all user-defined types; the ellipsis (...) can not be used correctly in the strongly typed context of format, and thus the function call with arbitrary arguments is replaced by successive calls to an argument feeding operator%.
• Lexical Cast: General literal text conversions, such as an int represented a string, or vice-versa.
• Regex: Regular expression library.
• Spirit: LL parser framework represents parsers directly as EBNF grammars in inlined C++.
• Tokenizer: Break of a string or other character sequence into a series of tokens.

Containers

• Array: STL compliant container wrapper for arrays of constant size.
• Dynamic Bitset: The dynamic_bitset class represents a set of bits. It provides accesses to the value of individual bits via an operator[] and provides all of the bitwise operators that one can apply to builtin integers, such as operator& and operator<<. The number of bits in the set is specified at runtime via a parameter to the constructor of the dynamic_bitset.
• Graph: The BGL graph interface and graph components are generic, in the same sense as the the Standard Template Library (STL).
• Multi-Array: Boost.MultiArray provides a generic N-dimensional array concept definition and common implementations of that interface.
• Property Map: Concepts defining interfaces which map key objects to value objects.
• Variant: Safe, generic, stack-based discriminated union container.

Iterators

• Graph: The BGL graph interface and graph components are generic, in the same sense as the the Standard Template Library (STL).
• Iterator: The Boost Iterator Library contains two parts. The first is a system of concepts which extend the C++ standard iterator requirements. The second is a framework of components for building iterators based on these extended concepts and includes several useful iterator adaptors.
• Operators: Templates ease arithmetic classes and iterators.
• Tokenizer: Break of a string or other character sequence into a series of tokens.

Algorithms

• Graph: The BGL graph interface and graph components are generic, in the same sense as the the Standard Template Library (STL).
• Utility: Class noncopyable plus checked_delete(), checked_array_delete(), next(), prior() function templates, plus base-from-member idiom.

Function objects and higher-order programming

• Bind: boost::bind is a generalization of the standard functions std::bind1st and std::bind2nd. It supports arbitrary function objects, functions, function pointers, and member function pointers, and is able to bind any argument to a specific value or route input arguments into arbitrary positions.
• Function: Function object wrappers for deferred calls or callbacks.
• Functional: The Boost.Function library contains a family of class templates that are function object wrappers.
• Lambda: Define small unnamed function objects at the actual call site, and more.
• Member Function: Generalized binders for function/object/pointers and member functions.
• Ref: A utility library for passing references to generic functions.
• Signals: Managed signals & slots callback implementation.
• Utility: Class noncopyable plus checked_delete(), checked_array_delete(), next(), prior() function templates, plus base-from-member idiom.

Generic Programming

• Call Traits: Defines types for passing parameters.
• Concept Check: Tools for generic programming.
• Enable If: Selective inclusion of function template overloads.
• Operators: Templates ease arithmetic classes and iterators.
• Property Map: Concepts defining interfaces which map key objects to value objects.
• Static Assert: Static assertions (compile time assertions).
• Type Traits: Templates for fundamental properties of types.

Template Metaprogramming

• MPL: The Boost.MPL library is a general-purpose, high-level C++ template metaprogramming framework of compile-time algorithms, sequences and metafunctions. It provides a conceptual foundation and an extensive set of powerful and coherent tools that make doing explict metaprogramming in C++ as easy and enjoyable as possible within the current language.
• Static Assert: Static assertions (compile time assertions).
• Type Traits: Templates for fundamental properties of types.

Preprocessor Metaprogramming

• Preprocessor: Preprocessor metaprogramming tools including repetition and recursion.

Concurrent Programming

• Thread: Portable C++ multi-threading.

Math and numerics

• Integer: The organization of boost integer headers and classes is designed to take advantage of <stdint.h> types from the 1999 C standard without resorting to undefined behavior in terms of the 1998 C++ standard. The header <boost/cstdint.hpp> makes the standard integer types safely available in namespace boost without placing any names in namespace std.
• Interval: Extends the usual arithmetic functions to mathematical intervals.
• Math: Boost.Math includes several contributions in the domain of mathematics: The Greatest Common Divisor and Least Common Multiple library provides run-time and compile-time evaluation of the greatest common divisor (GCD) or least common multiple (LCM) of two integers. The Special Functions library currently provides eight templated special functions, in namespace boost. The Complex Number Inverse Trigonometric Functions are the inverses of trigonometric functions currently present in the C++ standard. Quaternions are a relative of complex numbers often used to parameterise rotations in three dimentional space. Octonions, like quaternions, are a relative of complex numbers.
• Math Common Factor: Greatest common divisor and least common multiple.
• Math Octonion: Octonions.
• Math Quaternion: Quaternions.
• Multi-Array: Boost.MultiArray provides a generic N-dimensional array concept definition and common implementations of that interface.
• Operators: Templates ease arithmetic classes and iterators.
• Random: A complete system for random number generation.
• Rational: A rational number class.
• uBLAS: uBLAS provides matrix and vector classes as well as basic linear algebra routines. Several dense, packed and sparse storage schemes are supported.

Correctness and testing

• Concept Check: Tools for generic programming.
• Static Assert: Static assertions (compile time assertions).
• Test: Support for simple program testing, full unit testing, and for program execution monitoring.

Data structures

• Any: Safe, generic container for single values of different value types.
• Compressed Pair: Empty member optimization.
• Tuple: Ease definition of functions returning multiple values, and more.
• Variant: Safe, generic, stack-based discriminated union container.

Domain Specific

• CRC: The Boost CRC Library provides two implementations of CRC (cyclic redundancy code) computation objects and two implementations of CRC computation functions. The implementations are template-based.
• Date Time: A set of date-time libraries based on generic programming concepts.

Input/Output

• Format: The format library provides a class for formatting arguments according to a format-string, as does printf, but with two major differences: format sends the arguments to an internal stream, and so is entirely type-safe and naturally supports all user-defined types; the ellipsis (...) can not be used correctly in the strongly typed context of format, and thus the function call with arbitrary arguments is replaced by successive calls to an argument feeding operator%.
• IO State Savers: The I/O sub-library of Boost helps segregate the large number of Boost headers. This sub-library should contain various items to use with/for the standard I/O library.

Inter-language support

• Python: The Boost Python Library is a framework for interfacing Python and C++. It allows you to quickly and seamlessly expose C++ classes functions and objects to Python, and vice-versa, using no special tools -- just your C++ compiler.

Memory

• Pool: Memory pool management.
• Smart Ptr: Smart pointer class templates.
• Utility: Class noncopyable plus checked_delete(), checked_array_delete(), next(), prior() function templates, plus base-from-member idiom.

Parsing

• Spirit: LL parser framework represents parsers directly as EBNF grammars in inlined C++.

Patterns and Idioms

• Compressed Pair: Empty member optimization.
• Signals: Managed signals & slots callback implementation.
• Utility: Class noncopyable plus checked_delete(), checked_array_delete(), next(), prior() function templates, plus base-from-member idiom.

Programming Interfaces

• Function: Function object wrappers for deferred calls or callbacks.

System

• Date Time: A set of date-time libraries based on generic programming concepts.
• Filesystem: The Boost Filesystem Library provides portable facilities to query and manipulate paths, files, and directories.
• Thread: Portable C++ multi-threading.

Miscellaneous

• Conversion: Polymorphic and lexical casts.
• Lexical Cast: General literal text conversions, such as an int represented a string, or vice-versa.
• Optional: Discriminated-union wrapper for optional values.
• Timer: Event timer, progress timer, and progress display classes.
• Utility: Class noncopyable plus checked_delete(), checked_array_delete(), next(), prior() function templates, plus base-from-member idiom.
• Value Initialized: Wrapper for uniform-syntax value initialization, based on the original idea of David Abrahams.

Broken compiler workarounds

• Compatibility: Help for non-conforming standard libraries.
• Config: Helps Boost library developers adapt to compiler idiosyncrasies; not intended for library users.