Shady site Shady site not sure if the team behind are trustworthy with holding your algos data. I found other frameworks like backtrader that are easier to pick up and get working with quickly than LEAN. LEAN is poorly documenting making learning a huge hurdle. Also, I question the stability of their site because of the amount of bugs you can find in their UI and some that I encountered in plotting during backtrading. If you need an online IDE, Quantopian is far more reliable and documented and quicker to work with but still could have issues with data privacy.

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

Great technology, accessible team, invaluable supporters of the ecosystem QuantConnect has been an invaluable partner for my personal trading and for a university class that I teach. The community is incredibly supportive, and the leadership team are accessible which is almost unheard of in trading platforms these days. In my class, my graduate level students have been able to personally engage and implement constructs like Fama French factors, and QuantConnect has been an active supporter to facilitate my students learning. It's incredible to join the community, have access to a variety of detailed trading algorithms, instructional videos, and see my students feel confident implementing week-to-week. I don't think there's anything like QuantConnect out there today, and I'm a big supporter of their efforts. I can't imagine my own trading or teaching my class without it!

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.

Have been using QC for 3 years Have been using QC as an individual for 3 years, has been a smooth and consistent experience the entire time. Quantconnect makes building a trading algorithm highly accessible to anyone with an idea and a bit of coding knowledge. Handling all the background infrastructure for you, they make it easy to build your algorithm, backtest against market data, and even deploy it live with a supported brokerage. Sometimes it can be a bit difficult to learn the syntax and what a method does, but there is a lot of documentation available, as well as community forums. All this has really helped me focus on my strategy rather than building infrastructure from the ground up and I would definitely recommend them to anyone looking to try out quant finance or algorithmic trading.