I have previously traded in a demo account using FP Markets since they have an education centre where they offer in-depth daily technical and fundamental analysis, which will definitely help beginners venturing into FX.
For demo trading broker I recommend to use Avatrade or FP Markets since they provide educational materials like e-books, video tutorials, live webinars and others.
All brokers offer free demo accounts for practice purposes, but you should demo trade with a broker whom you want to go live with. I opened demo accounts with turnkey forex and lqdfx because of their low trading costs and that is how I went live after that - so in my opinion, go with one you want to use for live trading.
Many brokers do provide demo accounts for free. I can recommend a couple of brokers like Avatrade and FP Markets that also provide educational materials, webinars, and video tutorials for newbies venturing into forex for the first time.
I suggest one can research brokers offering ECN zero spreads. Then compare the brokers' plans, fees and offering. What works for you then try their demo platform because any demo platform will give you hands on practicing, real-time account will only expose to the real trading conditions then.
for using demo account traders can choose at any broker , this is not necessary to choose a broker when trading in a demo.
demo account can be used to check out a broker trading condition so just try out with different brokers.