Cryptocurrency — entry 018 of 53
CoinCap
CoinCap serves real-time and historical price, market cap, and volume data for thousands of assets plus a WebSocket feed for live trades and price updates, originally built to power CoinCap's own portfolio app. What was once a fully open, keyless API now requires a free API key for REST endpoints, with CoinCap Pro adding higher rate limits and pay-per-call access via the x402 payment protocol.
AuthenticationAPI KeySign up with the provider to obtain credentials.
HTTPSSupportedTraffic is encrypted in transit.
CORSEnabledCallable directly from browser JavaScript.
PricingFreemiumA usable free tier exists, with paid plans for more volume.
FormatsJSON, WebSocketResponses can be requested as JSON or WebSocket.
GreatAPIs Score
Score67
Authentication15/25API key required
Pricing17/20Freemium tier available
Docs0/20No docs or spec available
Formats15/15Supports 2 response formats
Freshness20/20Verified within 6 months
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<a href="https://greatapis.com/api/coincap/"><img src="https://greatapis.com/badge/coincap.svg" alt="Scored 67 on greatapis.com"></a>Auth quickstart
- Sign up with the provider to get an API key.
- Send it on every request as a header
Authorization: <key> - The exact header isn't documented — Authorization is a common default; confirm in the provider's docs.
Stored keyNo key stored
Your key is stored only in this browser (localStorage) and sent directly to the API — never to greatapis.