I Turned a Free API Into a $200/Month Side Project

The API existed. People needed it. They just didn't want to figure it out themselves.

The Origin Story

Last year I was building a crypto tracking dashboard. I needed real-time price data, signals, and historical performance metrics.

The problem? Every exchange has a different API format. Some use REST, some WebSocket, some GraphQL. Authentication varies wildly. Rate limits are all over the place.

I spent two weeks just normalizing data from 5 exchanges.

Then it hit me: if I need this, other developers do too.

What I Built

A simple API wrapper that:

Aggregates data from multiple sources into one format

Caches responses (so you don't hit rate limits)

Handles authentication automatically

Returns clean, consistent JSON

Before (what developers do): ┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ Binance │ │Coinbase │ │ Kraken │ │ Bybit │ │ API │→ │ API │→ │ API │→ │ API │ └─────────┘ └─────────┘ └─────────┘ └─────────┘ ↑ Different auth ↑ Different…