// learn · Data & tools
Market data APIs & how to read docs
Most market data you'd pay for is available free if you know where to look, and reading API docs is a skill worth ten minutes to learn.
Free APIs worth knowing
- Yahoo Finance (via the yfinance library), stock prices, history and fundamentals, no key. Great for equities.
- CoinGecko, crypto prices, market caps and history, generous free tier.
- DexScreener, on-chain pairs and new listings (Peaky Radar uses it for new-listing detection).
How to read any API doc
- Endpoint, the URL you call, e.g.
/coins/markets. Docs list one per data type. - Parameters, the query options (symbol, range, currency). Required vs optional is always marked.
- Rate limits, how many calls per minute before you're blocked. Cache anything that rarely changes.
- Auth, free tiers often need no key; paid ones use an API key in a header. Never put a key in front-end code.
Start with one endpoint. Fetch a single price, print it, then build up. Most "the API doesn't work" problems are a wrong parameter or a hit rate limit, read the error, not the whole doc.
Ready to try it in code? See Yahoo Finance + Python.
Educational market information, not financial advice. Markets carry risk of loss, do your own research.