Blockchain API

Beginner's Pick Cryptocurrency / API Key Intermediate HTTPS
Varies by plan (check documentation)

Overview

Blockchain.com Explorer API provides read access to Bitcoin blockchain data including individual transaction details, block information, and wallet address summaries. The public endpoints are free to use and return JSON data on confirmed transactions, UTXOs, and block contents. It is widely used by educators and developers who want to inspect Bitcoin network activity without running a full node.

Beginner Tip

Most read endpoints need no API key — try fetching a transaction directly by ID using https://blockchain.info/rawtx/YOUR_TX_HASH?format=json. For higher rate limits and access to wallet management features, register for a free API key at blockchain.com/api.

Available Data

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

Example Response

JSON Response
{
  "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

hash Unique 64-character hexadecimal identifier of this block.
height Block number counting from the genesis block at height 0.
time Unix timestamp when the block was mined.
tx List of all transactions included in this block.
n_tx Total number of transactions in this block.
size Block size in bytes before segwit witness data.

Implementation Example

Request
// ⚠️ Note: This URL may be a documentation page. Check official docs for actual API endpoint.
const url = "https://www.blockchain.com/api";
// Replace headers or query params with the values required by this API.
const response = await fetch(url, {
  headers: {
  "X-API-Key": "YOUR_API_KEY"
  }
});
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

429 or Cloudflare block after repeated requests The public tier enforces aggressive rate limiting to prevent scraping.
Add at least a 1-second delay between requests and cache results; if you need bulk access, register for an API key.
Transaction not found (404) Unconfirmed transactions may not yet be in the mempool index, or the TX hash is incorrect.
Double-check the full 64-character hex hash and note that very recent unconfirmed transactions may have a propagation delay.
Incorrect address balance shown The API returns the total received amount, not the current balance; you must subtract total_sent.
Calculate balance as final_balance or use the dedicated address summary endpoint which returns final_balance directly.

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 API Key
HTTPS REQUIRED
CORS UNKNOWN
Category Cryptocurrency
Difficulty Intermediate
Verified: 2026-04-07

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