Covalent provides a unified API to bring full transparency and visibility to assets across all blockchain networks including Blockchain.

To get started, sign up for an API Key.

Developer Mode (JSON) Analyst Mode (CSV)
Developer Mode Analyst Mode

The Covalent API is RESTful and offers the following out-of-the-box for Blockchain:

Covalent API
Response formats JSON and CSV
Real time response 2 blocks
Batch response 30 minutes
Request volume limit None
Request rate limit 5 requests per second
Base URL
Networks & chain_id Mainnet - 1
Testnet - 42
Supported Endpoints Class A
- Balances
- Transactions
- Transfers
- Token Holders
- Log Events (Contract Address)
- Log Events (Topic Hash)

Try the supported endpoints directly in your browser from our API Reference or use the following code examples. The JSON response format is the same for all endpoints:

    "data": ..., 
    "error": false,
    "error_message": null,
    "error_code": null


curl -X GET "{YOUR API KEY}" -H "Accept: application/json"


const baseURL = ''
const blockchainId = 1
const demoAddress = '0xFEC4f9D5B322Aa834056E85946A32c35A3f5aDD8'

async function getWalletBalance(chainId, address) {
    const url = new URL(`${baseURL}/${chainId}/address/${address}/balances_v2/?key=${APIKEY}`);
    const response = await fetch(url);
    const result = await response.json();
    const data =;
    return data;

// Example address request
getWalletBalance(blockchainId, demoAddress);


import requests
base_url = ''
blockchain_id = 1
demo_address = '0xFEC4f9D5B322Aa834056E85946A32c35A3f5aDD8'

def get_wallet_balance(chain_id, address):
    endpoint = f'/{chain_id}/address/{address}/balances_v2/?key={API_KEY}'
    url = base_url + endpoint
    result = requests.get(url).json()
    data = result["data"]

# Example address request
get_wallet_balance(blockchain_id, demo_address)

Use Cases

The Covalent API supports a broad range of Web3 data use cases including:

Gaming DeFi KYC NFT
Gaming DeFi Taxes KYC NFTs
Wallets Dashboards On-Chain Forensics DAO
Wallets Dashboards On-Chain Forensics DAO Data
Trading Predictions Governance Pricing
DEXs & Trading Predictive Analytics Governance Pricing

Check out our collection of ready-to-ship Code Templates that you can use to build your Web3 data-powered dApps.



Here are some additional resources to help you get started with the Covalent API:


About Covalent

Covalent provides the industry-leading Unified API bringing visibility to billions of Web3 data points. Developers use Covalent to build exciting multi-chain applications like crypto wallets, NFT galleries, and investor dashboard tools utilizing data from 32+ blockchains. Covalent is trusted by a community of 27,000+ developers and powers data for 1000+ applications including 0x, Zerion, Rainbow Wallet, Rotki, Bitski and many others.

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Last modified: October 5, 2022: september-changelog-2022 (#237) (7fb89f6)