What is an API?

An API, or Application Programming Interface, is essentially a bridge that allows two different software programs to communicate with each other. Think of it as a waiter in a restaurant – the waiter takes your order (request), tells the kitchen what you want, and then brings the food (response) back to you. Similarly, an API receives a request from one software, sends it to another system, and then returns the response to the original requestor.

How Does It Work in Crypto?

Imagine you're using a crypto exchange platform. APIs make it possible for that platform to communicate with other services, like wallets, price tracking sites, or even blockchains themselves. Here's how:

  • Request: A user or app sends an API call to perform actions like checking a wallet balance, fetching prices, or placing a trade.
  • Processing: The API processes the request, communicating with a blockchain or crypto exchange to retrieve data or execute tasks.
  • Response: The API returns the requested information, such as market prices or transaction confirmations.
    Crypto APIs enable real-time interactions, powering trading platforms, wallets, and DeFi applications.

Types of APIs in Crypto

  • Public APIs: These are open to everyone. For example, an API that provides the latest crypto prices. Anyone can use it.
  • Private APIs: Restricted to authorized users, often requiring an API key. Exchanges use these to secure access to user-specific data like trading history.
  • RESTful APIs: The most common type of API in crypto, known for their simplicity and use of HTTP protocols.
  • WebSocket APIs: Perfect for real-time updates, such as live crypto prices or trading data.

Common Uses of APIs in Crypto

  • Price Tracking: Get the latest crypto prices across exchanges.
  • Trading Bots: Automatically execute trades on crypto exchanges using pre-set strategies.
  • Portfolio Management: Pull data from various wallets and exchanges to give users an overview of their crypto holdings.

Other Glossary Terms

DeFi

DeFi, or decentralized finance, refers to blockchain-based apps that offer financial services without banks. It runs on smart contracts, giving users full control over their assets.

Blockchain trilemma

The blockchain trilemma is the challenge of achieving scalability, security, and decentralization at the same time. Learn why it matters — and how projects try to balance the trade-offs.

Crypto Address

A crypto address is a unique identifier used for sending and receiving cryptocurrency on blockchain networks. Linked to a wallet

Public Blockchain

A public blockchain is an open, decentralized network where anyone can participate, validate transactions, and view the ledger. Learn how it works, its benefits, and the challenges it faces in scalability and security.

Circulating Supply

Circulating supply is the number of crypto tokens actively available in the market. It impacts price, market cap, and scarcity, making it a key metric for investors. Bitcoin has ~19.5M BTC circulating, while Ethereum's supply fluctuates.

Block in a blockchain

A block in a blockchain is a digital record that contains a batch of verified transactions, along with metadata such as a timestamp, cryptographic hash, and a reference to the previous block.