
InstaPart
Circuito.io
B4R
library.io
embedXcode
Atmel Studio
XOD
Zerynth
CodingInterview
AlgoExpert.io
Interview Cake
interviewing.io
Daily Coding Problem
Codechef
CodeForces
LogicMojo
Circuito.io - Instant code and wiring for your project
AlgoExpert.io - A better way to prep for tech interviews
B4R - Development tool for native Arduino programs.
Interview Cake - Free practice programming interview questions. Interview Cake helps you prep for interviews to land offers at companies like Google and Facebook.
library.io - Learn electronics and easily create circuit boards online
interviewing.io - Free, anonymous technical interview practice