Package/Framework for (Finance) Broker Alike Web Application?

I am not sure this is the right place to ask for recommendation. If not, please let me know. I will delete my post.

If I want to have a website to allow user to place trades, view market charts, etc (just like all the retail banks offer to their customers to trade stock).

I am looking for:
1. customize-able
2. small memory footprint and low CPU usage on the server side
3. CentOS 7 friendly
4. mobile friendly
5. basic (fancy isn't necessary)

There will be at most 100 users going to use the website. Hence, don't have to be very scalable.

What do you recommend?