Hi. I have ideas for an improved equity-index futures charting platform, and experience developing charting platforms. PM if you are asking on behalf of a well-funded group that seeks competitive advantage, not to mass-market a platform.
You might want to read the 10,000 hour thread, because having gone through the process of working on a new platform architecture, desktop and mobile, like trading no one has any idea how complex the whole thing is. You can build a proof of concept relatively quickly, but to make it production ready is something only those with deep pockets or very niche requirements do. There are 100s of ways to do anything, so either you have a specific algo which is built in to the tool, eSignal Advanced Get, or you have a generic tool such as MT4 or some of the more advanced platforms. We have niche, and are expanding out to generic, you really want to make a new platform design the 'last resort' option.
I decided to give up on trading after developing full-featured Forex Simulator software. It may be a good start for a new trading platform. It's fast and visually attractive, it has great charting, indicators and drawing tools, as well as simulated order execution engine. It will not be hard to develop a server part for it, taking into account that it's just a database, connection channel and some business logic. Highly optimized C# code can be really fast. I also have enough experience in both speed/memory optimization and developing client/server solutions from my previous business (keyword research tools). I served 3,000+ customers from a single custom built server sitting at my kitchen while my competitors paid up to $100,000/mo for AWS. You can find the link in my profile.
You will be surprised, but the downtime of my kitchen server was almost the same as my hetzner server and S3 storage in the last few years, taking into account various power outages and problems in all these places. I'm absolutely serious. In my 20+ years of business my "safely hosted servers" at third-party sites were burned to ashes, flooded by water, stolen, arrested by FBI because they were close to some other questionable server, they got numerous router problems, not even counting dead HDDs or broken memory modules.