The replacement of delphi, based on the Free Pascal kernel, is similar to the Delphi development tool Lazarus.

License: GPL/LGPL
Lazarus is a Free Pascal class library similar to Delphi. free Pascal is a compiler that runs in Linux, Win32, OS/K, and more systems under the (L) GPL 'convention. free Pascal is designed to be compatible with the Delphi syntax, that is, OOP.
Lazarus will make it easier for you to design programs on all platforms like Delphi. IDE will eventually become RAD like Delphi.

Lazarus Official Website: www.lazarus.freepascal.org

After the trial, it is found that the compilation speed is very slow and the size of the default compilation is relatively large. You can use strip -- strip-all to reduce the size by 60%.

This is some of its Screenshots

IDE Windows	Compiling	Object Inspector-Properties	Object Inspector-Events	Debugger-All Windows	Debugger-Breakpoints
Debugger-Callstack	Debugger-Locals	Debugger-Watches	Compiler Options-Search Paths	Compiler Options-Parsing	Compiler Options-Code Generation
Compiler Options-Linking	Compiler Options-Other	Editor Options-General	Editor Options-Display	Editor Options-Key Mappings	Editor Options-Color
Editor Options-Code Tools	Environment Options-Desktop	Environment Options-Files	Environment Options-Backup	External Tools	Replace Dialog
Run Parameters	CodeTools Defines Editor	CodeTools Options-General	CodeTools Options-Code Creation	CodeTools Options-Line Splitting	CodeTools Options-Space
Sample of Lazarus running in Mac OSX

Free pascal is direct: http://jaist.dl.sourceforge.net/sourceforge/lazarus/fpc-2.0.2a.i386-win32.exe
Lazarus directly: http://jaist.dl.sourceforge.net/sourceforge/lazarus/Lazarus-0.9.16-20060528-win32.exe