VLVaneesa Lenzinfloat-forex.hashnode.dev·3d ago · 8 min readServing Real-Time Forex Rates Without Hammering Your API: A FastAPI + MongoDB Caching StrategyAny app that serves live data — currency rates, crypto prices, stock tickers, weather — eventually hits the same wall. Your upstream data provider has a rate limit. Your users don't. If every page loa00