Most developers assume that using a broker's API gives you a direct advantage when building financial tools.

The assumption: if your broker has an API, you might as well use it for data.

The reality: trading APIs and data APIs solve fundamentally different problems — and confusing the two will cost you weeks of unnecessary setup, a running desktop app, and a live brokerage account before you write a single line of analysis code.

If you're:

building a stock screener or portfolio analyzer,