The compilers, IDEs, and systems that programmers actually used.
Windows CE was Microsoft's compact operating system for handhelds, and the Pocket PC and Windows Mobile platforms built on it were Microsoft's pre-2010 answer to the PDA and smartphone, programmed with eMbedded Visual Tools and later the .NET Compact Framework.
A small, self-contained, serverless SQL database engine embedded directly in applications, and the most widely deployed database in the world.
Apache Subversion, the centralized version control system started in 2000 to be CVS done right, and the leading centralized tool of the 2000s before git.
The influential Java object-relational mapping framework that popularized mapping objects to relational tables and shaped the JPA standard.
JetBrains' Java and Kotlin IDE, first released in January 2001, that brought deep code analysis, navigation, and integrated refactoring into mainstream development and became the platform under Android Studio, PyCharm, and other tools.
The library of scientific algorithms (optimization, integration, signal processing, statistics, and more) built on top of NumPy arrays, and the namesake of the broader scientific Python ecosystem.
Apple's set of Objective-C application frameworks (AppKit plus Foundation) for macOS, descended directly from the NeXTSTEP and OpenStep object libraries acquired with NeXT.
The extensible, open-source Java IDE and plug-in platform created by IBM in 2001 and later stewarded by the Eclipse Foundation, built on the OSGi-based Equinox runtime and home to Erich Gamma's Java Development Tools.
Fernando Perez's enhanced interactive Python shell, begun in 2001, whose kernel architecture and rich interactive model became the engine inside Jupyter.
Microsoft's web framework for .NET, which evolved from Web Forms (2002) through MVC to the open-source, cross-platform ASP.NET Core.
Atlassian's issue- and project-tracking system, launched in 2002, which became dominant in commercial software teams and especially in agile workflows.
A macOS package manager modeled on the BSD ports system; the main way to install open-source software on the Mac before Homebrew.
The PHP wiki engine built to run Wikipedia; first written by Magnus Manske in 2002, it introduced templates, extensions, and the wikitext markup that scaled the wiki to the largest sites on the web.
Microsoft's managed application platform, built around the Common Language Runtime and a large class library, first released in early 2002 and later open-sourced and made cross-platform as .NET Core.
A distributed version-control system built on a novel theory of patches rather than snapshots, influential in design though never mainstream.
The dominant open-source real-time kernel for microcontrollers, created by Richard Barry in 2003 and now stewarded by Amazon; a tiny-footprint kernel offering tasks, queues, and a fixed-priority preemptive scheduler.
The foundational Python plotting library, whose MATLAB-like pyplot interface made publication-quality figures a built-in part of the scientific Python workflow.
Org mode, the Emacs major mode created by Carsten Dominik in 2003 for outlining, task management, agenda planning, literate programming, and document export, all from plain-text files.
The official repository of Python packages that pip installs from, and one of the largest language package registries.
The open-source machine emulator and virtualizer, started by Fabrice Bellard in 2003, that emulates whole computers and pairs with KVM for fast virtualization.
The dependency-resolving package tool for RPM-based Linux distributions, the apt-equivalent for the Red Hat world, later succeeded by DNF.
Apple's integrated development environment for macOS, iOS, and the rest of its platforms, descended from Project Builder and bundling Interface Builder, the iOS Simulator, and an LLVM/Clang toolchain.
The open-source hypervisor born at the University of Cambridge in 2003 that popularized paravirtualization and became the foundation of early cloud computing.
A free, open-source source-code editor for Windows created by Don Ho in 2003 and built on the Scintilla editing component. Long a default lightweight replacement for the built-in Windows Notepad among programmers.
A modular compiler and toolchain infrastructure, created by Chris Lattner, that underpins Clang, Swift, Rust, and many other languages.
A Java build tool that added a declarative project model (the POM) and automatic dependency management from a central repository.
Maven Central is the default public repository of Java and JVM artifacts, from which build tools like Maven and Gradle resolve dependencies.
JetBrains' productivity extension for Microsoft Visual Studio, first released in 2004, that brought on-the-fly code analysis, solution-wide refactoring, and fast navigation to .NET development.
Valve's 3D game engine, debuting in 2004 with Half-Life 2 as the successor to GoldSrc, whose SDK and Hammer editor enabled a large modding community and whose games were distributed through Steam.
A Python client/server system that runs and restarts long-lived programs on Unix-like systems at the project level, filling the gap where a full init system is unavailable or unwanted, such as inside containers and shared hosts.
ARM's family of low-power 32-bit processor cores for microcontrollers, introduced from the mid-2000s; with the Thumb instruction set and the nested vectored interrupt controller, it came to dominate modern embedded systems.
The Ruby package manager and gem format that standardized how Ruby libraries are packaged, shared, and installed.
Rod Johnson's lightweight dependency-injection container for Java, first released in 2003-2004, which displaced heavyweight J2EE and grew into the Spring ecosystem and Spring Boot.
Alex Papadimoulis's long-running site, also known as Worse Than Failure, that catalogues real-world bad code, disastrous IT projects, and 'enterprise' anti-patterns with humorous commentary.
David Heinemeier Hansson's convention-over-configuration MVC web framework, extracted from Basecamp in 2004, whose Active Record, scaffolding, and famous blog demo reshaped how web applications are built.
The Debian-based Linux distribution Canonical launched in 2004 to make desktop Linux approachable, known for its six-month time-based releases, LTS support, and the motto 'Linux for human beings.'
Mozilla's open-source web browser, whose 1.0 release in 2004 challenged Internet Explorer's monopoly and pushed the web back toward open standards.
An early document database that stores JSON, is queried with MapReduce views, and replicates so well it supports offline-first apps; known for its HTTP and REST API.
Arduino is an open-source electronics platform of simple microcontroller boards and a beginner-friendly IDE, created in Ivrea, Italy around 2005 to make physical computing accessible to artists, students, and hobbyists.
Luke Kanies's declarative, model-driven configuration-management system, first released in 2005, in which administrators describe desired system state in manifests written in Puppet's own DSL and an agent enforces it.
Canonical's distributed version-control system, used by Ubuntu and Launchpad, aimed at ease of use, and now largely historical.
Apple's object-graph management and persistence framework for macOS and iOS, which models an application's data as objects and commonly stores them in an SQLite database underneath.
The distributed version-control system Linus Torvalds wrote in 2005 to manage Linux kernel development, now the dominant way source code is tracked.
A distributed version-control system created in April 2005, known for a clean Python-based design, and for years git's main distributed rival.
The open-source browser engine behind Apple's Safari, forked from KDE's KHTML and fully open-sourced in 2005; Google's Chrome used it before forking off Blink.
fish, the friendly interactive shell, first released in 2005, is a Unix shell focused on usability. It ships with autosuggestions, syntax highlighting, and tab completion out of the box, and it deliberately breaks POSIX compatibility to provide a cleaner, more consistent scripting language.
A cross-platform game engine first released in 2005, scripted in C#, that lowered the cost of game development and became the dominant tool for indie and mobile titles.
The batteries-included Python web framework that grew out of newspaper development at the Lawrence Journal-World's World Online department and was open-sourced in summer 2005. Known for its ORM, automatic admin interface, and the Model-Template-View (MTV) pattern.