Free Pascal - Open source compiler for Pascal and Object Pascal

Free Pascal (aka FPK Pascal) is a 32 and 64 bit professional Pascal compiler. The language syntax has excellent compatibility with TP 7.0 as well as with most versions of Delphi (classes, rtti, exceptions, ansistrings, widestrings, interfaces). A Mac Pascal mode, largely compatible with Think Pascal and MetroWerks Pascal, is also available. Furthermore Free Pascal supports function overloading, operator overloading, global properties and several other extra features.