A free, open-source Pascal compiler started in 1993 when Borland abandoned DOS Pascal development. Originally called FPK-Pascal, it grew into a mature cross-platform compiler supporting Turbo Pascal and Delphi dialects across dozens of platforms.
Supports multiple Pascal dialects (Turbo Pascal, Delphi up to ~Delphi 7+, Objective Pascal, Apple Pascal) selectable per compilation unit. Targets 20+ CPU architectures including x86, x86-64, ARM, AArch64, MIPS, PowerPC, SPARC, RISC-V, and JVM. Features an internal linker for Windows targets, smart-linking/dead code elimination, and multiple optimization levels.
Free Pascal emerged in June 1993 when German student Florian Paul Klaempfl began developing his own Pascal compiler after Borland made clear that Borland Pascal 8 would not exist — the next product would be Delphi, a Windows-only RAD environment. Klaempfl wanted a free, 32-bit Pascal compiler compatible with the Turbo Pascal dialect for DOS. The project was initially called FPK-Pascal (from Klaempfl's initials) and was renamed Free Pascal Compiler (FPC) in late 1997.
The initial compiler was itself a 16-bit executable compiled by Turbo Pascal, targeting the GO32v1 DOS extender. After two years, the compiler achieved the critical milestone of self-compilation — building itself as a 32-bit executable. When published on the Internet, contributors joined: Michael van Canneyt created a Linux port (five years before Borland's own Kylix Pascal compiler for Linux), and Daniel Mantione contributed the OS/2 port.
Version 1.0, released in July 2000, was widely adopted in business and education. The 1.1.x branch (from December 1999) brought major rewrites of the code generator and register allocator, and importantly added full Delphi compatibility mode — allowing FPC to compile most Delphi code. From version 2.0 onward, Delphi compatibility has been continuously improved, with FPC sometimes implementing language features (like generics in 2.2.0) years before Delphi itself.
Free Pascal is not technically a 'fork' of Turbo Pascal's source code — it is a clean-room compatible reimplementation. However, it represents the most significant community response to a proprietary language platform being discontinued, and its Delphi compatibility mode has made it the de facto open-source alternative to Embarcadero's commercial products. It compiles for over 20 processor architectures and dozens of operating systems.
Florian Klaempfl begins developing FPK-Pascal
Compiler achieves self-compilation as 32-bit executable
First public release on the Internet
Renamed from FPK-Pascal to Free Pascal Compiler (FPC)
Version 1.0 released, widely adopted in business and education
Version 2.0 released with comprehensive Delphi compatibility mode
Version 2.2.0 adds generics support (before Delphi)
Version 3.0.0 adds JVM bytecode generation, ARM Android target
Became the primary open-source Pascal compiler, keeping the Pascal language alive and accessible after Borland's shift to commercial-only products. Enabled the Lazarus IDE project. Supports more platforms than any commercial Pascal compiler. Used by notable projects including Cheat Engine, PeaZip, and Beyond Compare (Linux/Mac versions).