Off the top of my head, look into Order Book Heatmaps, 3D Volatility Surfaces, Footprint Charts/Volatility deltas. Integrating drawing tools like Fibonacci Retracements, Gann Fans etc. It would make it very attractive to people willing to pay.
This comment was buried yesterday. I'm sorry for the late response!
I was thinking about a pro tier for this kind of specialized stuff. Core stays MIT forever, but fintech tooling could be paid.
Of the chart types you listed, is there a preference for what gets done first?
Order Book Heatmaps first?
Competitors typically have to snapshot/aggregate because their graphing libraries are heavily CPU bound. Being able visualise level 2/3 data without downsampling is a big win. Also being able to smoothly roll back through the last 12hrs of tick-level history would be really neat too.
I'd say the bare minimum feature set outside of that is going to be:
- Non linear X axis for gaps/sessions
- Crosshairs that snap to OHLC data
- Logarithmic scales, Candlesticks, Heikin-Ashi, and Volume profiles
- Getting the 'feel' nice so that you can quickly scale and drag (people are real sticklers for the feel of these tools)
- Solid callbacks for events for exchange integration, people hate leaving their charts to place an order eg (onOrderModify etc)
- Provide a nice websocket data ingestion pipeline
- Provide an api so devs can integrate their own indicators, some sort of 'layers' API or something.
Sorry if I can't be of more help as I'm just a hobbyist in this area!
BSL/BUSL seems like a good fit for licensing here. It's technically source available instead of open source but just adds the layer that a competitor can't be built using your core. Otherwise the core is free to modify and fork. AGPL might be an option but I fear it would scare off a lot of companies in the space who have policies against AGPL licensed code but you'd get to keep advertising as OSS.