[opensourcedex]

LibreOffice is a free, open source office suites project written in C++ and released under GPL-3.0. It has 4,373 GitHub stars, 945 forks and 0 open issues, and was last pushed 3 hours ago. On this registry it ranks #3 of 5 tracked projects in Office Suites, and is listed as an open source replacement for 1 paid product, with 5 head-to-head comparisons available. It gained 23 stars over the last 6 tracked days.

What is LibreOffice?

What it is

LibreOffice is an integrated office suite written in C++ and distributed under GPL-3.0. It lives in the open-source productivity and office suite ecosystem, and it positions itself as an open alternative to Microsoft 365. The Document Foundation backs the project as a community of enterprises, developers, and volunteers.

The project addresses the need for a free office suite that can be downloaded, used, and distributed while remaining compatible with most document formats and standards. The GitHub repository is a read-only LibreOffice core repo, so pull requests are not accepted; contributions use Gerrit, and source bundles are recommended over GitHub zip downloads.

Key capabilities

  • LibreOffice provides an integrated office suite based on copyleft licenses and compatible with most document formats and standards.
  • Extension development can use the SDK and the generic UNO APIs, which are also used by StarBasic macro scripting.
  • The project lists build and runtime baselines for Windows 10, macOS 11, Linux comparable to RHEL 9 or CentOS 9, iOS through LibreOfficeKit, Android, and browser WASM.
  • Build baselines include JDK 17 or later, Python 3.11, GCC 13 or Clang 18 on Linux, and Clang 18 for compiler plugins.
  • LODE scripts help set up initial build environments on Windows and macOS, and configure switches live in distro-configs.
  • The code base contains about two hundred modules, each expected to have a README.md file.

Who uses it and how

  • The Document Foundation community uses the project to develop and distribute a free office suite for personal productivity.
  • C++ programmers add features by working on the code base, which the README says is easier to build than the SDK path.
  • Extension developers use the SDK, API docs, and Developers Guide to build extensions that rely on UNO APIs.
  • Distributors obtain source bundles from https://dev-www.libreoffice.org/bundles/ and submit changes through Gerrit rather than pull requests.
  • Platform builders use stated toolchains such as Visual Studio 2022, Xcode, GCC 13, Clang 18, NDK 27, SDK 30.0.3, and Qt 5.15 with Emscripten 1.39.8.

Getting started

Typical use begins by downloading LibreOffice from the project homepage, while source distributions come from https://dev-www.libreoffice.org/bundles/ rather than GitHub zip files. Builders set up initial environments with LODE scripts for Windows and macOS and follow the TDF wiki build instructions.

When to use it — and when not to

LibreOffice is appropriate when the goal is a free, GPL-3.0 office suite that presents itself as an open alternative to Microsoft 365 and supports compatibility with most document formats and standards. Avoid a GitHub pull-request workflow, because the core repository is read-only and contributions go through Gerrit, and avoid WASM unless the browser supports SharedMemory with threads and atomics. The facts do not describe database, storage, SMTP, Docker, package-manager, or hosted server deployment, so those needs are outside the evidence shown here.

project readme (upstream, from github) — read inline

LibreOffice

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LibreOffice is an integrated office suite based on copyleft licenses and compatible with most document formats and standards. Libreoffice is backed by The Document Foundation, which represents a large independent community of enterprises, developers and other volunteers moved by the common goal of bringing to the market the best software for personal productivity. LibreOffice is open source, and free to download, use and distribute.

A quick overview of the LibreOffice code structure.

Overview

You can develop for LibreOffice in one of two ways, one recommended and one much less so. First the somewhat less recommended way: it is possible to use the SDK to develop an extension, for which you can read the API docs and Developers Guide. This re-uses the (extremely generic) UNO APIs that are also used by macro scripting in StarBasic.

The best way to add a generally useful feature to LibreOffice is to work on the code base however. Overall this way makes it easier to compile and build your code, it avoids any arbitrary limitations of our scripting APIs, and in general is far more simple and intuitive - if you are a reasonably able C++ programmer.

The Build Chain and Runtime Baselines

These are the current minimal operating system and compiler versions to run and compile LibreOffice, also used by the TDF builds:

  • Windows:
  • macOS:
    • Runtime: 11
    • Build: 13 or later + Xcode 14.3 or later (using latest version available for a given version of macOS)
  • Linux:
    • Runtime: RHEL 9 or CentOS 9 and comparable
    • Build: either GCC 13; or Clang 18 with libstdc++ 11
  • iOS (only for LibreOfficeKit):
    • Runtime: 14.5 (only support for newer i devices == 64 bit)
    • Build: Xcode 12.5 and iPhone SDK 14.5
  • Android:
    • Build: NDK 27 and SDK 30.0.3
  • Emscripten / WASM:
    • Runtime: a browser with SharedMemory support (threads + atomics)
    • Build: Qt 5.15 with Qt supported Emscripten 1.39.8
    • See README.wasm

Java is required for building many parts of LibreOffice. In TDF Wiki article Development/Java, the exact modules that depend on Java are listed.

The baseline for Java is Java Development Kit (JDK) Version 17 or later.

The baseline for Python is version 3.11. It follows the version available in SUSE Linux Enterprise Desktop and the Maintenance Support version of Red Hat Enterprise Linux.

If you want to use Clang with the LibreOffice compiler plugins, the minimal version of Clang is 18. Since Xcode doesn't provide the compiler plugin headers, you have to compile your own Clang to use them on macOS.

You can find the TDF configure switches in the distro-configs/ directory.

To setup your initial build environment on Windows and macOS, we provide the LibreOffice Development Environment (LODE) scripts.

For more information see the build instructions for your platform in the TDF wiki.

The Important Bits of Code

Each module should have a README.md file inside it which has some degree of documentation for that module; patches are most welcome to improve those. We have those turned into a web page here:

However, there are two hundred modules, many of them of only peripheral interest for a specialist audience. So - where is the good stuff, the code that is most useful. Here is a quick overview of the most important ones:

Module Description
sal/ this provides a simple System Abstraction Layer
tools/ this provides basic internal types: Rectangle, Color etc.
vcl/ this is the widget toolkit library and one rendering abstraction
framework/ UNO framework, responsible for building toolbars, menus, status bars, and the chrome around the document using widgets from VCL, and XML descriptions from /uiconfig/ files
sfx2/ legacy core framework used by Writer/Calc/Draw: document model / load/save / signals for actions etc.
svx/ drawing model related helper code, including much of Draw/Impress

Then applications

Module Description
desktop/ this is where the main() for the application lives, init / bootstrap. the name dates back to an ancient StarOffice that also drew a desktop
sw/ Writer
sc/ Calc
sd/ Draw / Impress

There are several other libraries that are helpful from a graphical perspective:

Module Description
basegfx/ algorithms and data-types for graphics as used in the canvas
canvas/ new (UNO) canvas rendering model with various backends
cppcanvas/ C++ helper classes for using the UNO canvas
drawinglayer/ View code to render drawable objects and break them down into primitives we can render more easily.

Rules for #include Directives (C/C++)

Use the "..." form if and only if the included file is found next to the including file. Otherwise, use the `` form. (For further details, see the mail Re: C[++]: Normalizing include syntax ("" vs ).)

The UNO API include files should consistently use double quotes, for the benefit of external users of this API.

loplugin:includeform (compilerplugins/clang/includeform.cxx) enforces these rules.

Finding Out More

Beyond this, you can read the README.md files, send us patches, ask on the mailing list [email protected] (no subscription required) or poke people on IRC #libreoffice-dev on irc.libera.chat - we're a friendly and generally helpful mob. We know the code can be hard to get into at first, and so there are no silly questions.

SAST Tools

PVS-Studio - static analyzer for C, C++, C#, and Java code.

Frequently asked questions

Is LibreOffice free to use?

LibreOffice is open source under the GPL-3.0 licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does LibreOffice do?

Free office suite with Microsoft compatibility

What is LibreOffice written in?

LibreOffice is primarily written in C++. Its source is publicly available at https://github.com/libreoffice/core, and it has 4,373 GitHub stars.

What is a good open source alternative to Microsoft 365?

LibreOffice is one of the open source options listed as an alternative to Microsoft 365. Compare licences, stars and activity side by side on the LibreOffice profile.