Blockchain.com API Getting Started Guide (2026)

Getting started overview

The Blockchain.com API provides programmatic access to Bitcoin blockchain data, enabling developers to integrate functionalities such as checking wallet balances, monitoring transactions, and retrieving block information directly into their applications. This guide outlines the process of setting up an account, obtaining necessary API credentials, and executing a foundational request.

The API primarily offers read-only access to Bitcoin blockchain data, focusing on explorer functionalities like transaction and address lookups. Access is managed through API keys, which are obtained after creating an account on the Blockchain.com platform. For a comprehensive overview of available endpoints and their specific parameters, refer to the Blockchain.com API documentation.

This quick start guide focuses on the immediate steps to make a first successful API call. For details on advanced usage, rate limits, or specific data models, the official documentation should be consulted.

Create an account and get keys

To access the Blockchain.com API, you must first create an account on the Blockchain.com platform. This account serves as your gateway to managing API keys and monitoring usage.

1. Register on Blockchain.com: Navigate to the Blockchain.com website and complete the registration process. This typically involves providing an email address and creating a password. Account verification, often via email, is usually required to activate the account.
2. Log in to your account: Once registered and verified, log in to your newly created Blockchain.com account.
3. Access the API Section: Within your account dashboard, locate the section related to API access or developer tools. The exact navigation may vary, but it is typically found under settings or a dedicated 'API' link.
4. Generate an API Key: In the API section, you will find an option to generate a new API key. This key is a unique alphanumeric string that authenticates your requests to the API. It is crucial to treat your API key as sensitive information, similar to a password, to prevent unauthorized access to your usage limits or potential malicious activity. Some platforms provide different types of API keys for various environments (e.g., development, production), though Blockchain.com's primary offering is a single key for all environments for its read-only data access. Copy this key immediately after generation, as it might only be displayed once for security reasons. If lost, you may need to generate a new key and revoke the old one.
5. Understand Usage Tiers (if applicable): While there is a free tier for basic use, higher request limits or specialized data access may require a custom plan. Review the available tiers and their associated limits to ensure your usage aligns with your project requirements.

It is best practice to store your API key securely, such as in environment variables, rather than hardcoding it directly into your application's source code. This practice, often referred to as managing API secrets, minimizes the risk of exposure if your code repository becomes compromised.

Your first request

With your API key in hand, you can now make your first request to the Blockchain.com API. A common starting point is to retrieve information about a specific Bitcoin address or transaction. For this example, we will retrieve information about a well-known Bitcoin address using a simple HTTP GET request.

The Blockchain.com API uses a RESTful architecture, meaning you interact with resources using standard HTTP methods like GET. Responses are typically formatted in JSON.

Example: Get a Bitcoin Address Summary

This example demonstrates how to retrieve the summary of a Bitcoin address, including its balance, total received, and total sent. You will replace YOUR_API_KEY with the key you generated.

Request Structure:

GET https://api.blockchain.info/haskoin-store/btc/address/1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa/transactions?api_code=YOUR_API_KEY

Using cURL (Command Line):

Open your terminal or command prompt and execute the following cURL command. Replace YOUR_API_KEY with your actual API key.

curl -X GET "https://api.blockchain.info/haskoin-store/btc/address/1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa/transactions?api_code=YOUR_API_KEY"

Expected JSON Response (partial example):

Upon a successful request (HTTP status 200 OK), the API will return a JSON object containing transaction details for the specified address. The exact content will depend on the address and the specific endpoint, but it will typically include transaction hashes, block heights, and input/output details.

[
  {
    "txid": "a1075db55d416d9247d48",
    "block_height": 123456,
    "size": 225,
    "virtual_size": 142,
    "version": 1,
    "locktime": 0,
    "vin": [
      {
        "txid": "previous_txid",
        "vout": 0,
        "script_sig": "...",
        "sequence": 4294967295
      }
    ],
    "vout": [
      {
        "value": 5000000000,
        "script_pub_key": "...",
        "addresses": [
          "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa"
        ]
      }
    ],
    "confirmations": 100000
  }
  // ... more transactions
]

This example demonstrates a request for transactions associated with a specific address. Other endpoints allow for retrieving block information, exchange rates, and more, as detailed in the Blockchain.com API reference documentation.

Common next steps

After successfully making your first API call, consider these common next steps to further integrate the Blockchain.com API into your development workflow:

1. Explore additional endpoints: The Blockchain.com API offers various endpoints beyond basic address lookups. Investigate endpoints for retrieving unconfirmed transactions, block details by hash or height, and current Bitcoin exchange rates. Each endpoint serves a different purpose for accessing blockchain data. Refer to the Blockchain.com API documentation to understand the full range of available data.
2. Implement API key management: For production applications, securely managing your API key is paramount. Avoid hardcoding the key directly into your application. Instead, use environment variables or a configuration management system to store and retrieve the key. This enhances security and simplifies key rotation.
   For example, in a Node.js application, you might use process.env.BLOCKCHAIN_API_KEY after setting the variable in your environment.
3. Error handling and rate limits: Implement robust error handling in your application to gracefully manage failed API requests. The API will return standard HTTP status codes (e.g., 400 for bad request, 401 for unauthorized, 429 for rate limit exceeded). Understand the rate limits imposed by Blockchain.com to avoid temporary blocks. Implement exponential backoff or similar strategies for retrying requests that fail due to transient issues or rate limiting.
4. Choose a client library: While direct HTTP requests are feasible, using an HTTP client library in your preferred programming language can simplify API interactions, handle JSON parsing, and manage request headers. Popular choices include requests for Python, axios or fetch for JavaScript, and HttpClient for Java or .NET.
5. Integrate with your application logic: Begin integrating the retrieved blockchain data into your application's core logic. This could involve displaying real-time transaction feeds, validating payment addresses, or tracking specific wallet activity. Ensure that your application's architecture accounts for the asynchronous nature of API calls.
6. Monitor API usage: Regularly monitor your API usage through your Blockchain.com account dashboard. This helps ensure compliance with usage limits and can provide insights into your application's performance and data consumption patterns.

Troubleshooting the first call

Encountering issues during your first API call is common. Here are some troubleshooting steps for typical problems when interacting with the Blockchain.com API:

1. Check API Key:
   • Is it correct? Double-check that you have copied the entire API key accurately without any leading or trailing spaces.
   • Is it active? Ensure the API key generated from your Blockchain.com account is active and has not been revoked. You might need to regenerate it if you suspect it's compromised or inactive.
   • Is it included? Verify that the api_code=YOUR_API_KEY parameter is correctly appended to your request URL, as demonstrated in the Your first request section. Forgetting to include the key will result in an unauthorized error.
2. Verify Endpoint URL:
   • Typographical errors: Even a small typo in the domain (e.g., blockchain.info vs. blockchain.com) or path can lead to a 404 Not Found error.
   • Correct endpoint for data: Ensure you are using the correct endpoint for the data you wish to retrieve. For example, requesting address transactions from a block endpoint will fail. Consult the Blockchain.com API documentation for specific endpoint paths.
   • Protocol: Always use https:// for secure communication.
3. Review HTTP Status Codes:
   • 400 Bad Request: Your request syntax is incorrect. Check parameters, headers, or body format.
   • 401 Unauthorized: This usually means your API key is missing or invalid. Recheck your key and its inclusion.
   • 403 Forbidden: Your API key might not have the necessary permissions for the requested resource, or your IP address might be blocked.
   • 404 Not Found: The requested resource (e.g., address, transaction hash) does not exist, or the URL path is incorrect. Verify the identifier you are querying.
   • 429 Too Many Requests: You have exceeded the API's rate limits. Wait for a period before retrying, or consider upgrading your plan if sustained higher usage is necessary.
   • 5xx Server Error: These indicate an issue on the API provider's side. While less common, these require waiting for the service to recover.
4. Check Network Connectivity:
   • Ensure your development environment has an active internet connection and no firewall or proxy is blocking outgoing HTTP requests to api.blockchain.info.
5. Examine Response Body:
   • Always inspect the full response body, even for error status codes. APIs often provide descriptive error messages in the JSON response that can pinpoint the exact issue.
   • For instance, a response might say {"error": "Invalid API Key"}, which is more specific than just a 401 status code. These are valuable for debugging and building robust error handling.
6. Consult Documentation and Community:
   • The official Blockchain.com API documentation is the authoritative source for endpoint specifics, error codes, and usage guidelines.
   • If you still face issues, search for similar problems on developer forums or communities. While Blockchain.com does not explicitly list community forums, general discussions about Bitcoin APIs on platforms like Stack Overflow might offer insights into common pitfalls with blockchain data APIs. For general API troubleshooting best practices, resources like the Google Developers API client library guide offer relevant advice on handling API calls.