We (getsimpl.com) use geektrust.in for developer hiring.
Developers create their profile, solve problems and earn badges. GeekTrust ensures companies have to engage with only people who are good at coding and solving problems. Companies pitch to candidates and if both matches, the next level of interviews are done by the company. It's great for companies as it improves the top-of-the-funnel with high-quality candidates.
For candidates, it's using their core skills to market themselves, at their pace. There're people who slowly build their profile. They submit code, get helpful reviews to go further.
The difference between GeekTrust and other coding platforms is that they handle things well beyond just plain problem-solving. Things like great design, documenting etc.
As mentioned by others, we use HackerRank also to evaluate different aspects.
All the best.