The Arduino IDE is recommended for beginners, hobbyists, educators, and anyone interested in developing small to medium-sized electronics projects. It's an excellent starting point for those looking to learn about microcontrollers and embedded systems without a steep learning curve.
Eclipse - Eclipse is an open source community, whose projects are focused on building an open development platform comprised of extensible frameworks, tools and runtimes for building, deploying and managing software across the lifecycle.
PlatformIO - Next-generation IDE for IoT
Netbeans - NetBeans IDE 7.0. Develop desktop, mobile and web applications with Java, PHP, C/C++ and more. Runs on Windows, Linux, Mac OS X and Solaris. NetBeans IDE is open-source and free.
Visuino - Visuino is a visual programming environment that lets you write programs from Arduino circuit boards.
IntelliJ IDEA - Capable and Ergonomic IDE for JVM
MINIBLOQ - miniBloq is an open source graphical programming environment for Multiplo™, Arduino™, physical computing devices and robots.