IMO
The best way to start trading is with "FREE" or "demo' money. What better way to learn than by TRADING?
I would strongly suggest anyone who wants to learn, dabble or whatever start this way.
Head over to simplefx sign up and use demo account... Save your money until you've learned a thing a two.
Full review of SimpleFx HereIf you mean altcoin trading then I haven't seen any "demo mode" in their website and these exchanges as far as I know do not provide such information, maybe it was on alpha mode when it was for testing purpose but right now not. As you have posted I have seen the demo mode only on forex and on similar websites.