Lazarus 4 is the latest version of the all-FOSS but Delphi-compatible IDE for the FreePascal compiler.

The Sons of Kahn and the assembly language of the internet [1]READ MORE

The [2]IDE is developed independently from the underlying Pascal language that it's written in, so this doesn't mean a whole new version of FreePascal: Lazarus 4 was built with [3]FreePascal 3.2.2 which was released in 2021. It replaces Lazarus 3.8, which was the current version when we talked about it for [4]Delphi's 30th anniversary back in February.

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Lazarus somehow manages to feel Windows-like even on a Mac, but it works – click to enlarge

Version 4 comes along relatively soon after the last new major version, [6]Lazarus 3.0 which came out in December 2023. The project's [7]Gitlab page has a long list of issues fixed in this release. The [8]version 4.0 release notes have a complete list of changes and new features. There are substantial changes in its various events and classes. Perhaps the most immediately visible change will be how the IDE handles [9]docking :

The IDE now comes with built-in docking and docked-form editor (they can be toggled as option, rather than rebuilding IDE to install/remove packages). When run for the first time the user will be prompted with a choice to enable them.

It's a multi-platform IDE, and the [10]Sourceforge page has packages for both 32-bit and 64-bit Windows, Linux, and FreeBSD. On Apple hardware, it offers PowerPC, x86 and Arm64 versions; Cocoa development needs macOS 12 or higher, but using the older Carbon APIs it supports OS X 10.5 to 10.14. There's also a Raspberry Pi version for the Pi 4 and later. It supports a wide variety of toolkits for GUI programming, as the [11]project wiki shows: Win32, Gtk2 and work-in-progress Gtk3, and Qt versions 4, 5 and 6, among others.

[12]Lightweight LXQt 2.0.0 updates to same toolkit as KDE Plasma 6

[13]Type-safe C-killer Delphi hits 30, but a replacement has risen

[14]RIP: Software design pioneer and Pascal creator Niklaus Wirth

[15]Nostalgic for VB? BASIC is anything but dead

One criticism we've seen of the FreePascal project in general concerns its documentation, although there is quite a lot of it: [16]eight FPC manuals , and [17]lengthy Lazarus docs in multiple languages. There is a paid-for [18]tutorial e-book available, too.

Something which might help newcomers to the language here is a new e-book: [19]FreePascal From Square One by Jeff Duntermann. The author says:

It's a distillation of the four editions of my Pascal tutorial, Complete Turbo Pascal , which first appeared in 1985 and culminated in Borland Pascal 7 From Square One in 1993. I sold a lot of those books and made plenty of money, so I'm now giving it away, in hopes of drawing more people into the Pascal universe.

He does have a caveat, though:

I need to mention here that the book does not go into Windows programming, OOP, software components, or the Lazarus GUI builder.

There are other free resources out there, such as this [20]course in Modern Pascal . The more, the merrier, though.

Pascal isn't cool or trendy any more, but even so, it remains in the top ten on the [21]TIOBE index . Perhaps these new releases will help it to rise up the ratings a little more. ®

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[1] https://www.theregister.com/2012/12/11/verity_stob_sons_of_kahn/

[2] https://forum.lazarus.freepascal.org/index.php/topic,71050.0.html

[3] https://wiki.freepascal.org/FPC_New_Features_3.2.2

[4] https://www.theregister.com/2025/02/19/delphi_turns_30/

[5] https://regmedia.co.uk/2025/05/09/lazarus_4_macos.jpg

[6] https://wiki.lazarus.freepascal.org/Lazarus_3.0_release_notes

[7] https://gitlab.com/freepascal.org/lazarus/lazarus/-/commits/fixes_4/

[8] https://wiki.freepascal.org/Lazarus_4.0_release_notes

[9] https://wiki.freepascal.org/Docking

[10] https://sourceforge.net/projects/lazarus/files/

[11] https://wiki.lazarus.freepascal.org/Roadmap

[12] https://www.theregister.com/2024/04/20/lxqt2_updates_to_qt6/

[13] https://www.theregister.com/2025/02/19/delphi_turns_30/

[14] https://www.theregister.com/2024/01/04/niklaus_wirth_obituary/

[15] https://www.theregister.com/2023/03/28/nostalgic_for_basic/

[16] https://www.freepascal.org/docs.html

[17] https://wiki.freepascal.org/Lazarus_Documentation

[18] https://www.blaisepascalmagazine.eu/product/learn-program-using-lazarus-electronic-pdf/

[19] https://www.contrapositivediary.com/?p=5399

[20] https://castle-engine.io/wp/2025/04/14/modern-pascal-course-examples-and-slides-updates-to-modern-pascal-book-to-fully-support-both-delphi-and-fpc/

[21] https://www.tiobe.com/tiobe-index/

[22] https://whitepapers.theregister.com/