Kandio is described as 'online platform that has a growing library of exams where you can choose which exams to give to your candidates applying for your job opening'. There are five alternatives to Kandio, not only websites but also apps for iPhone, Chrome OS, SaaS and Windows. The best alternative is HackerRank. It's not free, so if you're looking for a free alternative, you could try HackerEarth. Other great sites and apps similar to Kandio are CodeSignal (Paid), Geektastic (Paid) and CodeSubmit (Paid).
CodeSignal is the leading provider of assessments for technical hires. As the creator of the Predictive Coding Score, a measure of a candidates coding skills, CodeSignal provides HR teams with Certified Assessments, Custom Tests, and Live Interviews.