Overview

CoinCap delivers real-time cryptocurrency prices and market data for thousands of assets through a straightforward REST API. No API key is required for most endpoints, making it one of the easiest crypto APIs to start with. It also offers a WebSocket feed for live price streaming without polling.

Beginner Tip

Fetch the current Bitcoin price with no signup at all: curl https://api.coincap.io/v2/assets/bitcoin — the id field in the URL matches the asset slug, not the ticker symbol.

Available Data

The kind of data this API exposes, based on its documentation. We could not call the endpoint to confirm the exact field names.

coin price in USD/EUR
market capitalization
24h price change
trading volume
circulating supply

Example Response

Illustrative shape only — we were not able to call this endpoint (it requires credentials or exposes no public sample URL), so the fields below show the kind of data this API returns rather than a recorded response.

JSON Response · Illustrative
{
  "id": "bitcoin",
  "symbol": "btc",
  "current_price": 65432.1,
  "market_cap": 1280000000000,
  "price_change_24h": 1250.5,
  "price_change_percentage_24h": 1.95,
  "total_volume": 28500000000
}

Field Reference

data.id Unique slug identifier for the asset (e.g., bitcoin).
data.symbol Short ticker symbol (e.g., BTC).
data.priceUsd Current price in USD as a high-precision decimal string.
data.marketCapUsd Total market capitalization in USD.
data.changePercent24Hr Percentage price change over the last 24 hours (can be negative).
data.volumeUsd24Hr Total trading volume in USD across all exchanges in the past 24 hours.

Implementation Example

Calls a real endpoint of this API. Replace any placeholder credentials with your own key.

Request
const url = "https://docs.coincap.io/";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

Generated guidance based on this API's documentation, not observed by us. Treat it as a starting point and check against the provider's own error reference.

Asset not found (empty data field) Using a ticker symbol (e.g., BTC) instead of the slug (bitcoin)
Query /v2/assets?search=bitcoin to discover the correct slug for any coin, then use that in /v2/assets/{id}.
Rate limit exceeded Sending more than ~200 requests per minute on the unauthenticated tier
Register for a free API key to get higher limits; add the Authorization: Bearer YOUR_KEY header.
CORS error in browser fetch HTTP instead of HTTPS causing mixed-content block
Always use https://api.coincap.io — CoinCap supports CORS on HTTPS but not HTTP.

Metadata Score Breakdown

Estimated from metadata — endpoint not independently tested

This score is estimated from observable metadata — HTTPS support, authentication model, declared CORS, and documentation reachability — because the API requires authentication or exposes no publicly testable endpoint. The five-signal breakdown is only shown for live-tested APIs.

Metadata estimate · endpoint not independently tested

Technical Specifications

Auth No Auth
HTTPS REQUIRED
CORS UNKNOWN
Category Cryptocurrency
Difficulty Beginner
Listing details not endpoint-verified

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