Actually Exchange is a trading platform but if any one "don't have money to invest or some one want to learn trading without investing money" this was the thought i was having that time and i thought new users will learn trading .. for this project i hired a free lancing company. that time they shared a pdf called legal agreement. for a six months they worked for me and they given progress as well once i payed 70% of money they left with code and my servers doesn't have any code & their phone numbers are not reachable
Probably all forex brokers offer demo trading on their platform. Many of them use universal software, MetaTrader (MT4 or MT5), although I have seen the possibility of demo trading on some crypto platforms as well. (it would be really interesting to see the implementation of the MT platform in full crypto exchanges) the idea itself is not particularly exclusive.
as an individual, it will be very difficult for you to start a startup of this type. With the success of the course.
if your primary goal is to bring in beginners who want to learn something about trading, then maybe you could present yourself as some kind of online trading academy, where you offer free courses. You would probably have to create a lot of material (video, guides "how-to", etc...) for learning about trading. although I think the internet is already overwhelmed with various advice and tips from some self-declared experts.
if you are really skilled in trading, then opens up the possibility that one day when you create a reputation, you can have a paid part of the training.
next, for a real trading platform that should attract real traders, it takes a lot more. it is very difficult to persuade established traders to move from a system that already works to something completely new and unconfirmed. you would probably have to make some concessions that the competition does not offer. Low trading fee, low or no withdrawal fee etc...
you definitely need a lot of money to make it all happen, and a large customer base.
if your developers have taken the code, it makes you insecure at first. you can't be sure they didn't leave the back door and that it will not be abused someday. so I would say you are at the beginning, especially if you don’t have a loyal customer base which is the biggest value of this type of business.