CoinGecko's API delivers real-time and historical cryptocurrency data, covering prices, market cap, trading volume, and NFT floor prices for over 18,000 coins across 200+ networks. It offers RESTful JSON endpoints with a free Demo plan (30 calls/min, 10,000 calls/month) and paid plans starting at $129/month (500 calls/min, 500,000 calls/month). Key features include on-chain DEX data, portfolio tracking, and reliable aggregation from 1,000+ exchanges.