Practically everyone who has worked with an Arduino or Arduino-compatible board has started with the "Arduino IDE." After a couple of years of development, Arduino introduced the IDE 2.0 beta in March 2021. This beta represented a significant re-work of the 16-year-old software. Now, the team is releasing Arduino IDE 2.0 Release Candidate and asking for your help to test them.
Version 2.0 is not a minor update by any definition. Development transitioned from a Java environment to Theia, a cloud and desktop IDE platform. Theia is open source, modular, and built with modern technologies. The result is a refined user interface, continued cross-platform compatibility, and commonality between the desktop IDE and Arduino Web Editor. Another change is that the Arduino command-line interface (Arduino CLI) now handles the build process on the back end. This change should improve support for more microprocessor architectures.
From a user's perspective, the feature-set available in the 2.0 IDE is roughly the same. When launched, the code section dominates the window with compiler output on the bottom. Tools like the Serial Monitor and Serial Plotter are still available and feature quality-of-life improvements.
On the left is a toolbar that has taken cues from modern IDEs. There, you can find the Sketch Book, Library Manager, Board Manager, and Debugger (that's new!) are easily accessible without obstructing the code.
Despite the significant changes under the hood, the new Arduino IDE's best feature is still around: the "Zero-to-Blink" time is as short as possible. Overall, everything just feels "nicer" with 2.0.
As with the previous version, this one continues as an open sourced project. The source code and revision history are available in the arduino-ide GitHub repository. As with many open source projects, areas unrelated to code development need your help. For example, the Arduino Team asks for help regarding Localizations, a new (and welcomed) addition to 2.0.
Release Candidate 2 is available for download on Arduino.cc right now! Check out this blog post for more details and a video demo of the new serial plotter. After you try it out, you can provide feedback to the team using this Arduino IDE 2.0 feedback form.