What is a Blockchain API?
A blockchain API allows developers to interact with blockchain networks without running their own nodes. It provides methods to query data, send transactions, and deploy smart contracts through simple HTTP requests or WebSocket connections.
Types of Blockchain APIs
JSON-RPC API
The foundation of blockchain communication. Most networks expose a JSON-RPC interface:
// Example: Get ETH balance
curl -X POST https://eth-mainnet.g.alchemy.com/v2/YOUR_API_KEY \
-H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","method":"eth_getBalance","params":["0x...","latest"],"id":1}'REST API
More user-friendly APIs that wrap JSON-RPC with additional features:
- Alchemy - View Pricing
- Infura - View Pricing
- QuickNode - Fast global CDN
WebSocket API
Real-time data streaming for updates:
// Subscribe to new blocks
wscat -c wss://eth-mainnet.ws.alchemy.com/v2/YOUR_API_KEY
{"jsonrpc":"2.0","method":"eth_subscribe","params":["newHeads"],"id":1}Getting Started Steps
- Choose a Provider - Sign up for Alchemy, Infura, or QuickNode
- Get API Keys - Create your free account and retrieve keys
- Test Connection - Use the API to query basic data
- Build Your App - Integrate into your application
💡 Pro Tip: Start with free tiers. Alchemy offers 20M compute units free, Infura provides 100K requests/day.
Popular Use Cases
- Reading wallet balances and transaction history
- Submitting transactions to the blockchain
- Listening for smart contract events
- Building NFT marketplaces
- Creating DeFi dashboards
Best APIs for Beginners
We recommend starting with these providers based on ease of use and free tier availability:
- Alchemy - Best developer experience, excellent docs
- Infura - Industry standard, reliable
- QuickNode - Fast performance, global infrastructure