Free Pascal-based integrated development environment (IDE) based on and compatible with Borland's Delphi program and the Lazarus Component Library (LCL) libraries, which are equivalent to VCL. As in Delphi 7, the creation of program windows is done using the drag-and-drop method, the components are arranged on the window area. Quick transitions between different interfaces and systems are provided by The Interface libraries.

The following interface types are currently supported: WIN32 GDI, GTK+ 1.2.x (Unix, Mac OS X), GTK+ 2.x, Qt 4 (C++) and Windows CE. A big advantage of the application is the possibility to use it in closed code projects.

In addition, Lazarus is one of the few tools enabling the creation of applications for PDA devices (Windows CE, Qtopia). Over time, the authors intend to add full support for PalmOS and Symbian OS.