Circuito.io - Instant code and wiring for your project
Arduino IDE - Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware...
Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
B4R - Development tool for native Arduino programs.
VoltSim - VoltSim is an interactive realtime circuit simulator. It has digital and analog components and even Integrated Circuits. It is the perfect companion to students, hobbyists, and engineers.
PlatformIO - Next-generation IDE for IoT