Lazarus - Delphi Like, Open Source

Free Pascal (FPC) is an open-source Pascal compiler with two notable features: a high degree of Delphi compatibility and availability on a variety of platforms, including Windows, Mac OS X, and Linux. Free Pascal's compatibility with Delphi includes not only support for the same Object Pascal programming language that Delphi uses, but also for many of the same libraries of powerful routines and classes that Delphi is justly known for. This includes familiar units such as System, SysUtils, StrUtils, DateUtils, Classes, Variants, Math, IniFiles and Registry, which are included with Free Pascal on all supported platforms. Free Pascal also includes units such as Windows, ShellAPI, BaseUnix, Unix and DynLibs for accessing features specific to an operating system. These dozen or so units make up the core of what is usually referred to as the Free Pascal run-time library (RTL).

Lazarus is an open-source development system that builds on the Free Pascal compiler by adding an integrated development environment (IDE) that includes a syntax-highlighting code editor and visual form designer, as well as a component library that's highly compatible with Delphi's Visual Component Library (VCL). The Lazarus Component Library (LCL) includes equivalents for many of the familiar VCL controls such as forms, buttons, text boxes and so on that are used to create applications that have a graphical user interface (GUI).

Both Free Pascal and Lazarus are written in Pascal. Complete source code is available not only for the Free Pascal compiler and Lazarus IDE, but also for all units that make up the Free Pascal RTL and Lazarus LCL.

Like Delphi, Free Pascal and Lazarus are both general-purpose programming tools, meaning you can develop a wide variety of programs with them, including the following: