When I first went to wire up a stock data feed, Alpha Vantage looked like the obvious default: it's free, it's a real API, and it covers a huge swath of assets. So I wrote my pipeline against it — and then discovered two things that changed how I think about any free financial data feed. First, the free tier is rate-limited so tightly (I measured roughly 5 requests per minute) that any loop needs a sleep between calls. Second, and bigger for me: it doesn't cover Japanese stocks at all, which is the market I actually needed. Checked and confirmed in my own setup.

The free tier is a scheduling constraint, not a firehose

The headline "free" hides a real operational constraint. On the free tier I observed roughly 5 requests per minute, which is fine if your job makes a handful of calls.…