Build native apps with
Lazarus IDE
The free, open-source RAD environment for cross-platform development in Object Pascal. Write once, compile for Windows, macOS, Linux, and more.
unit Unit1;
interface
uses
Classes, SysUtils, Forms,
Controls, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
Label1: TLabel;
procedure Button1Click(Sender: TObject);
end;
implementation
procedure TForm1.Button1Click;
begin
Label1.Caption := 'Hello, World!';
end;What is Lazarus?
A modern IDE for Object Pascal developers
Lazarus was designed to give Object Pascal developers a productive, Delphi-like experience while removing platform and licensing barriers. The goal is simple: one language, one codebase, native output everywhere.
Open-Source IDE / RAD
Lazarus is a free, open-source Rapid Application Development environment distributed under the LGPL and GPL licences. Anyone can use, study, modify, and redistribute it.
Powered by Free Pascal
Lazarus compiles with Free Pascal (FPC), a mature, high-performance compiler that targets a wide range of operating systems and CPU architectures.
Object Pascal, Naturally
The IDE and the applications you build are written in Object Pascal — a readable, statically-typed language with a rich object model and decades of proven use in production software.
Cross-Platform from Day One
A single codebase compiles and runs natively on Windows, Linux, macOS, BSD, and more — without emulation, without a virtual machine, and without rewriting your UI for each target.
“Write once, compile anywhere.”Lazarus IDE — the open-source RAD for Object Pascal
Core Strengths
Everything you need to build real applications
Lazarus brings together a productive IDE, a powerful compiler, and a rich component library — all without any licensing fees.
Open Source
Licensed under LGPL/GPL. Full source code available. No vendor lock-in.
Cross-Platform
Target Windows, Linux, macOS, BSD, and more from a single project.
Free Pascal Powered
Built on FPC — a mature, fast, self-hosting compiler with broad architecture support.
Rapid Visual Development
Drag-and-drop form designer with integrated property inspector and component palette.
Object Pascal Compatible
Native support for Object Pascal syntax, generics, interfaces, and modern language features.
Delphi-Like Workflow
Familiar project structure, form editor, and coding model for developers migrating from Delphi.
Cross-Compilation
Compile for x86, x64, ARM, PowerPC, MIPS, SPARC, and more from any supported host OS.
Active Community
Decades of accumulated knowledge — forums, mailing lists, wikis, and hundreds of packages.
The Compiler
How Lazarus works with Free Pascal
Lazarus is the IDE and visual tooling layer. Free Pascal is the engine that turns your Object Pascal source into native machine code. Together, they form a complete development stack for building production applications without any cost or licensing fees.
The compiler behind Lazarus
Lazarus relies entirely on Free Pascal (FPC) to compile your code. FPC is a production-grade, self-hosting compiler with over 30 years of active development.
Multiple OS and CPU targets
FPC can target Windows, Linux, macOS, BSD, iOS, Android, and more. Supported architectures include x86, x64, ARM, ARM64, PowerPC, MIPS, SPARC, and 68000.
Native, high-performance output
Applications compiled with FPC are native executables — no virtual machine, no interpreter, no runtime overhead. Fast startup, low memory footprint, real OS integration.
Lazarus Component Library
The LCL — cross-platform components, one API
The Lazarus Component Library (LCL) is a rich set of visual and non-visual components inspired by Delphi's VCL. It was redesigned from the ground up to support cross-platform development: your application code calls the LCL API, and the LCL delegates to the appropriate native widgetset for the current platform.
This architecture separates your application logic from the graphical subsystem. You write code once against the LCL API, and the rendering is handled natively by GTK, Qt, Win32, Cocoa, or whichever widgetset is active.
Architecture
Sample components
Hundreds of additional components are available through the Lazarus package manager (OPM).
Widgetsets
Native look and feel on every platform
The LCL delegates rendering to a widgetset that maps to the native graphical toolkit of the target OS. Choose the right one for your deployment target.
| Widgetset | Primary use | Status |
|---|---|---|
| Win32/Win64 | Windows applications | stable |
| GTK2 | Linux and BSD | stable |
| GTK3 | Modern Linux / BSD | stable |
| Qt4 | Cross-platform | legacy |
| Qt5 | Cross-platform | stable |
| Cocoa | macOS | stable |
| fpGUI | Lightweight environments | experimental |
| NoGUI | Headless / server | stable |
| Custom Drawn | Portable / mobile | experimental |
Cross-Platform
One codebase, many destinations
Free Pascal and Lazarus support an unusually wide range of operating systems and CPU architectures — from modern desktops to legacy and embedded environments.
OSOperating Systems
CPUCPU Architectures
Comparison
Lazarus vs Delphi
Both tools share the same language roots. The choice depends on your priorities — this table presents the differences factually.
| Aspect | Lazarus IDE | Delphi |
|---|---|---|
| Licence | Free / Open-Source (LGPL + GPL) | Commercial — subscription or perpetual |
| Language | Object Pascal (Free Pascal dialect) | Object Pascal (Embarcadero dialect) |
| Cross-platform | Windows, Linux, macOS, BSD, and more | Windows (primary), macOS, iOS, Android via FireMonkey |
| Cross-compilation | Compile for any supported target from any host | Platform-specific builds; cross-compilation is limited |
| Source availability | Full source — IDE, compiler, and LCL | Partial — RTL source included, compiler is closed |
| IDE experience | Functional, Delphi-like; actively improved | Polished, mature; strong tooling ecosystem |
| Documentation | Community wiki, forums, FPC docs | Extensive official docs, dedicated support |
| Community | Global open-source community; public forums | Commercial vendor + partner ecosystem |
| VCL compatibility | LCL — API-compatible in many areas; migration guide available | VCL is native; Windows-only |
This comparison is provided for informational purposes. Details may vary across versions. Delphi is a registered trademark of Embarcadero Technologies.
Project History
More than 25 years of development
Lazarus began in 1999 as a community response to the lack of a free, open-source IDE for Object Pascal developers. The name itself carries meaning — the project was conceived as a resurrection of an earlier, failed attempt named Megido.
From those early beginnings, Lazarus has grown into a mature and reliable IDE that runs on a wider range of platforms than most commercial counterparts.
- 1997–1998
Megido — the predecessor
A group of developers attempted to create an open-source Delphi clone called Megido. The project struggled and was eventually abandoned, leaving no usable result.
- 1999
Lazarus is born
Lazarus was started as a fresh attempt to build an open-source IDE for Free Pascal. The name was chosen deliberately — a project "raised from the dead" after Megido's failure, referencing the biblical story of Lazarus.
- 2000–2001
Early public releases
Initial versions appeared on SourceForge. The project attracted early adopters from the Pascal and Delphi community who saw the value of a free, cross-platform alternative.
- 2001–2010
Steady growth
The project gained stability. The LCL matured, the form designer became usable, and cross-platform support for Linux and Windows solidified. A growing community of contributors joined.
- 2010–2020
Maturity and broadening platform support
macOS support improved significantly with the Cocoa widgetset. Cross-compilation became a well-documented feature. Dozens of third-party component packages were published.
- 2020–2025
Modern era
Lazarus continued to track Free Pascal releases. HiDPI improvements, GTK3 and Qt5 widgetsets, and ongoing IDE refinements kept the toolchain competitive for everyday development.
- February 2026
Lazarus 4.6.0 released
The latest stable release, version 4.6.0, was published on February 25, 2026. Development remains active with regular releases and an engaged global community.
Get Started
Download Lazarus 4.0
Free to download, free to use, free to distribute. Choose your platform below.
Documentation
Everything you need to learn and build
A wealth of documentation, tutorials, and community resources — accumulated over more than two decades of open-source development.
Getting Started
Install Lazarus, create your first project, and run your first application.
Tutorials
Step-by-step guides covering forms, controls, databases, and more.
LCL Reference
Complete API documentation for the Lazarus Component Library.
Cross-Compilation
Set up your environment to compile for a different OS or CPU architecture.
Migrating from Delphi
A practical guide to porting VCL applications to Lazarus and the LCL.
FAQ
Answers to the most common questions about Lazarus and Free Pascal.
Community Forum
Ask questions, share projects, and get help from the global Pascal community.
Git Repository
Browse the source code, report issues, and submit merge requests on GitLab.
FAQ
Frequently asked questions
Answers to the most common questions about Lazarus and Free Pascal.
An open-source project under active development.
Lazarus is built entirely by volunteers and contributors from around the world. Every contribution — big or small — moves the project forward and helps Object Pascal developers everywhere.
Report bugs
Found an issue? File a detailed bug report on the GitLab issue tracker.
Submit patches
Fix bugs or implement features — submit a merge request on GitLab.
Improve documentation
Contribute to the Lazarus wiki — tutorials, guides, and API docs.
Test releases
Try pre-release builds and report regressions before they reach stable.
Publish packages
Share reusable components via the Online Package Manager (OPM).
Join the forum
Help other developers, share knowledge, and discuss ideas.
Support Lazarus Development
Lazarus is a 100% free and open-source project, developed and maintained by volunteers from around the world. Your donations help cover server costs, infrastructure, and enable contributors to dedicate more time to development.
Every contribution, no matter the size, makes a difference and keeps the project alive.
Thank you to all our supporters who make Lazarus possible. Your generosity fuels open-source innovation.