Apex teaches investing: fundamental and technical analysis, portfolio construction, risk management, trading psychology. The teaching material was worth little without live charts to teach on, and the obvious shortcut, embedding a third-party charting widget, was ruled out. They wanted the charts to be part of their own product rather than an iframe pointing at somebody else’s.
That turned a website project into a software project. We had to source raw market data, render every pixel ourselves, and make the result survive browsers that block the data provider outright.
Technical depth
The reported symptom was “charts not loading”. The actual cause was a single corrupt saved drawing, a one-anchor Fibonacci in localStorage, throwing on every repaint. Fixed with anchor validation on both save and load, a per-drawing try/catch that self-repairs, and per-layer error isolation so one bad element can never take down the whole chart.
Browsers frequently block the upstream data provider. We wrote a local relay that proxies both the websocket and the REST scanner, and compiled 58 symbols by 900 daily bars plus a 480-stock registry into a static snapshot, so charts and ticker still work from a bare file path.
A late websocket reply could satisfy a different symbol’s request. Every request now carries a unique series id, so replies can never cross over.
Firefox’s line-mode wheel events zoomed roughly 40 times too hard. Wheel deltas are normalised, zoom is proportional to the gesture, bar pitch recomputes on resize, and the price-axis drag was made exponential and pivoted on the grabbed price so a long drag cannot invert the axis.
The platform is in production and the engagement is continuing. We hold the codebase we wrote, so new indicators, new pages and new data sources are incremental work on a system we know rather than a rebuild. That is the shape most of our client relationships take once the first system is live.
Capability used: Software Development
The systems we are proudest of started as the piece nobody else wanted to quote on. Tell us what it is and we will come back with a scope, a fixed price, and an honest answer about whether we are the right people for it.
