APIs That Don't Need Authentication (Just Curl and Go)

I spent 30 minutes setting up OAuth for an API I needed once. Then I discovered there are dozens of APIs where you just... make a request. No key. No signup. No OAuth dance. Here are the best ones I've found. Financial Data (No Key!) CoinGecko — Crypto prices for 13,000+ coins curl -s 'https://api.coingecko.com/api/v3/simple/price?ids=bitcoin,ethereum&vs_currencies=usd' { "bitcoin" :{ "usd" : 67234 }, "ethereum" :{ "usd" : 3456 }} SEC EDGAR — Every public company's filings curl -s 'https://data.sec.gov/submissions/CIK0000320193.json' -H 'User-Agent: MyApp me@email.com' Apple's 10-K, 10-Q, 8-K filings going back decades. Free. US Treasury — National debt in real-time curl -s 'https://api.fiscaldata.treasury.gov/services/api/fiscal_service/v2/accounting/od/debt_to_penny?sort=-record_date&page[size]=1' Weather & Geo (No Key!) Open-Meteo — Weather forecasts + 80 years of history curl -s 'https://api.open-meteo.com/v1/forecast?latitude=40.71&longitude=-74.01&current_weather=true' IP Geoloca