A class browser is a feature of an integrated development environment (IDE) that allows the programmer to browse, navigate, or visualize the structure of object-oriented programming code.

Most modern class browsers owe their origins to Smalltalk, one of the earliest object-oriented languages and development environments. The typical Smalltalk "five-pane" browser is a series of horizontally-abutting selection panes positioned above an editing pane, the selection panes allow the user to specify first a category and then a class, and further to refine the selection to indicate a specific class- or instance-method the implementation of which is presented in the editing pane for inspection or modification.

Most succeeding object-oriented languages differed from Smalltalk in that they were compiled and executed in a discrete runtime environment, rather than being dynamically integrated into a monolithic system like the early Smalltalk environments. Nevertheless, the concept of a table-like or graphic browser to navigate a class hierarchy caught on.

With the popularity of C++ starting in the late-1980s, modern IDEs added class browsers, at first to simply navigate class hierarchies, and later to aid in the creation of new classes. With the introduction of Java in the mid-1990s class browsers became an expected part of any graphic development environment.

All major development environments supply some manner of class browser, including

Modern class browsers fall into three general categories: the columnar browsers, the outline browsers, and the diagram browsers.

Continuing the Smalltalk tradition, columnar browsers display the class hierarchy from left to right in a series of columns. Often the rightmost column is reserved for the instance methods or variables of the leaf class.

Systems with roots in Microsoft Windows tend to use an outline-form browser, often with colorful (if cryptic) icons to denote classes and their attributes.