Complex, difficult API, slow backtesting Extremely slow backtesting and very complex APi with bad documentation - be ready to spend many hours trying to understand the overly complex API that is changing all the time. And did I mention that support costs? So if a anything is complex you won't get answers from the staff unless you PAY them. I give them 2 stars as they have reasonably reliable data. The platform itself is only worth one star. note: if you ask about slowness or any other thing negative on their forum they delete the posts.

Accelerator of analysis! Really nice platform to boost your algorithmic trading.

Alex stayed the course and helped me… Alex stayed the course and helped me with an issue that turned out to be not QuantConnect’s fault. But it turns out his idea led to a resolution. Much appreciation!!!

I have been using QuantConnect for over… I have been using QuantConnect for over a year now. I started out using their free tier, which basically lets you do everything that you need to do to get started and more (coding, backtesting, access to historical data). Due to this I was able to learn how to use platform at my own pace without feeling pressured by any fees or costs. When I first started the documentation was still pretty spotty and it was difficult at first but I have always received fast and detailed replies by their staff and other community members, they have since improved their documentation and I have improved from being a beginner on the platform to being one of the helpful community members, I couldn't be happier with how QuantConnect and my own trading journey is evolving!

Long time believer, first time promoter. I've been using Quantconnect for about two years but they've just released new capabilities for options research, based on user feedback, that prompted me to add a review. They listen to, care about, and build new features for their users (free features). Highly recommend.