Blockchain API
Mainnet + Sepolia
Base API
The Crypto APIs Base API, part of the Blockchain API, lets you read balances, token transfers and blocks on Base and send transactions without running a node. One API key covers mainnet and sepolia. Webhooks tell your server when a payment confirms, and we never hold your private keys.
What can you do with the Base API?
Read balances and history
Confirmed balances and transactions for any Base address, and blocks.
Work with tokens
Read or prepare Base token transfers through the same API.
Estimate fees
Fee recommendations for slow, standard and fast confirmation on Base.
Prepare and broadcast
We build the unsigned transaction. You sign it, and we send it to the network.
Get webhooks
We call your URL when coins arrive at an address and when the transaction confirms.
Same shape on 35+ networks
Swap base for another chain in the path, such as Optimism or Arbitrum.
How do I get the latest Base block?
Send one GET request with your API key; the same request works on sepolia when you replace mainnet with sepolia in the path.
- Base URL
https://rest.cryptoapis.io - Auth: the X-API-Key header
- JSON responses, same shape on every chain
curl https://rest.cryptoapis.io/blocks/evm/base/mainnet/latest/details \ -H "X-API-Key: YOUR_API_KEY"
const res = await fetch( "https://rest.cryptoapis.io/blocks/evm/base/mainnet/latest/details", { headers: { "X-API-Key": process.env.CRYPTOAPIS_KEY } }, ); const { data } = await res.json(); console.log(data.item);
import os, requests r = requests.get( "https://rest.cryptoapis.io/blocks/evm/base/mainnet/latest/details", headers={"X-API-Key": os.environ["CRYPTOAPIS_KEY"]}, ) print(r.json()["data"]["item"])
{
"height": 234324,
"hash": "0x6b1fdd6357845016fb238d1bd58992a01b01c94e668f55e9502d65f0a50ac021",
"transactionsCount": 23432,
"timestamp": 1681893875
}
Which Base endpoints are available?
The main calls. Every path takes the network: mainnet or sepolia.
/blockchain-events/base/mainnet/address-coins-transactions-confirmedHow do I send a Base transaction without giving up my keys?
Crypto APIs never holds your private keys. You keep signing; we do the rest.
- Step 1 Prepare We build the unsigned transaction with the fee set.
- Step 2 Sign locally You sign on your own servers. Keys never leave.
- Step 3 Broadcast We push the signed transaction to the Base network.
- Step 4 Confirm A webhook tells you when it confirms.
Base API vs Base RPC: which do I need?
Most apps start with the API. Use RPC when you need a method the node exposes directly.
Base RPC
Need raw node calls (JSON-RPC)? NodeGrid RPC will give you one endpoint with automatic failover between partner providers. Until then, JSON-RPC access is part of the Blockchain API.
Explore NodeGrid RPCCheck a Base address for AML risk
A free risk band and sanctions check for any Base address is coming soon. Today, screen addresses with the AML API.
Coming soonWhat makes Base blockchain different?
Base, an Ethereum L2 platform, enables swift integration of EVM codebases and assets from Ethereum L1, Coinbase and other chains, ensuring cost-effectiveness and security.
Base, an Ethereum L2 platform, ensures security, stability, and scalability for on-chain applications. Any EVM codebase can be deployed to allow onboarding users and assets from Ethereum L1, Coinbase, and other chains. Integration with existing tools thanks to EVM compatibility is made possible. Additionally, its rollup architecture reduces user costs by 10x.
Other EVM chains, same request shape
Base API questions
Is there a free Base API?
You can try it free for 14 days. The Blockchain API free trial covers Base and every feature, with no card. It ends after 14 days or when its credits run out; after that, calls need a subscription, listed on the pricing page.
How do I get the balance of a Base address?
Call the address balance endpoint with the address; it returns the confirmed ETH balance. Token balances live in the token contracts, so list the address's token transfers to see them.
How do I broadcast a Base transaction?
Sign the transaction on your own server, then send the signed raw transaction to the broadcast endpoint, authenticated with your API key, and Crypto APIs pushes it to the Base network and returns the transaction ID. We can prepare the unsigned transaction for you first.
Do you support Base sepolia?
Yes. Every Base endpoint works on mainnet and sepolia. Change mainnet to sepolia in the path; the same API key works on both.
What makes Base different to work with?
It is an account-model EVM chain — every address has a single balance and a nonce. Tokens live in their own contracts rather than in the account balance, so reading them means calling the token contract; and every transaction needs the account's next nonce, which the same API returns.
How do I know when a Base transaction is confirmed?
Create a webhook subscription for the address. Crypto APIs calls your URL when a transaction to or from it confirms on Base.
Start building on Base today
14-day free trial, mainnet included. No card needed.