The best crypto APIs for developers

Introduction

Blockchains are revolutionizing how we store and manage data. These distributed databases allow numerous participants to add records and read the blockchain’s contents. However, directly interacting with blockchains like Solana, Ethereum, and Arbitrum can be a complex task for developers, particularly when it comes to reading and writing data. To simplify this process, numerous companies have created APIs (Application Programming Interfaces) that provide easier ways to communicate with blockchains.

In this post, we will explore the two major functionalities that companies typically need when working with blockchains: reading and writing. We will also provide an overview of the best API providers that offer solutions to achieve these tasks.

What do you want to do on a blockchain?

At its core, interacting with a blockchain is similar to interacting with any database — you want to read from it and write to it. Let’s dive into what reading and writing to a blockchain actually entails.

Reading from a blockchain

When reading from a blockchain, you are querying the blockchain’s data for specific information. The main types of data you might want to read include:

1. Account Data:

   • Wallet Balance: Information about how much ETH or a specific token an address holds.

   • Transaction Count (Nonce): The number of transactions sent from an address.
     
     

2. Transaction Data:

   • Sender & Receiver: Details about who sent and received the transaction.

   • Value Sent: The amount of cryptocurrency or tokens that were transferred.

   • Gas Used: The amount of gas consumed during the transaction.

   • Block Number: The block in which the transaction was included.

   • Transaction Hash: A unique identifier (like a receipt) for the transaction.

   • Input Data: Information related to smart contract interactions.
     
     

3. Block Data:
   Useful for analytics or building blockchain explorers. This includes:

   • Timestamp: When the block was mined.

   • Miner Address: Who mined the block.

   • Transactions in the Block: A list of all transactions in a block.

   • Gas Limits/Used: The gas limit set for the block and the gas used by transactions.

   • Parent Block: To trace the history of blocks.
     
     

4. Smart Contract State and Events:
   Smart contracts often emit events to track state changes. These can include:

   • Event Logs: Logs emitted by a smart contract whenever an action happens (e.g., transferring tokens, minting NFTs, etc.).

Writing to a blockchain

Writing to a blockchain means altering the state of the blockchain. This includes actions that change the data stored on the blockchain and can include:

1. Sending Tokens:

   • Transferring cryptocurrency (e.g., ETH, BTC) from one wallet to another updates the balance of the sender and recipient.

     
     

2. Interacting with Smart Contracts:

   • Smart contracts can be called to change values, transfer tokens, mint/burn NFTs, or trigger specific workflows.

     
     

3. Token Transfers:

   • Instead of sending ETH or BTC, this involves transferring tokens such as ERC-20 tokens (like USDC, DAI) or ERC-721 tokens (like CryptoKitties). You are interacting with a smart contract that manages the token’s rules and logic.
     
     

4. Voting and Governance Actions:

   • On-chain applications like DAOs allow users to vote or propose changes, which updates the state of the contract and emits events.
     
     

5. Minting or Burning NFTs:

   • Minting creates new tokens, while burning destroys them.

To perform these operations on a blockchain, you must communicate with a blockchain node.

RPC (remote procedure call) and blockchain nodes

A Remote Procedure Call (RPC) is a protocol that allows you to interact with a blockchain remotely. Instead of running your own node, you connect to a remote node (often provided by a third-party service like Infura or Alchemy) and use RPC calls to query and modify blockchain data.

A blockchain node is essentially a computer that participates in the blockchain network by storing, verifying, and sometimes producing new blocks. There are different types of nodes:

• Full Node: Keeps a complete copy of the entire blockchain.

• Light Node: Stores only a subset of the blockchain’s data.

• Mining/Validator Node: Creates new blocks (depending on the blockchain’s consensus mechanism).

Common RPC calls for the Ethereum ecosystem include:

• eth_blockNumber: Fetch the latest block number.

• eth_getBalance: Check an address’s ETH balance.

• eth_sendTransaction: Send a transaction (write to the blockchain).

• eth_call: Execute a smart contract function without altering the state (read-only).

While an RPC is essential for writing data to the blockchain, you might prefer using APIs for reading data from a blockchain. APIs offer access to blockchain-related information in a simplified and aggregated form, which can be useful for tasks like fetching market prices, token data, and more.

For example, you may hear the term “blockchain indexer.” These indexing companies are specialized API providers. They have done the hard work of aggregating and cleaning blockchain data. They then put that data into a form that is easily queryable, making reading blockchain data significantly easier. Here are a few examples of indexers that allow for reading of blockchain data:

• The Graph: A decentralized protocol for querying and indexing blockchain data, enabling developers to build dApps without managing complex infrastructure.

• Space and Time: Provides a blockchain indexing service that transforms data from major blockchains into relational tables for real-time and historical queries.

• Allium: Delivers enterprise-grade blockchain data solutions with real-time APIs and tools for analytics, powering applications for companies like Visa and Uniswap.

• ZettaBlock: Delivers real-time infrastructure for Web3 data indexing and analytics, enabling the creation of low-latency APIs for applications.

Oftentimes, these indexing or subgraph reading services will be part of a broader offering that also allows for writing data on chain. As a result, we need to better understand the difference between API and RPC providers.

API vs. RPC: What's the difference?

While both RPCs and APIs allow you to interact with blockchain data, there is a significant difference:

• RPCs give you real-time access to the blockchain’s state. You can query specific addresses, blocks, or transactions directly from the blockchain.

• APIs, such as those provided by CoinMarketCap and the indexers mentioned above, aggregate on-chain data and provide data feeds. These APIs give you information like cryptocurrency prices, volume, market caps, and historical trends. They typically don't provide direct access to the blockchain’s raw state but offer a simplified version of the data.

Why use blockchain APIs?

Using blockchain APIs provides several benefits:

• Simplicity: You don’t need to manage complex blockchain nodes yourself.

• Scalability: Handle large-scale requests and data storage with ease.

• Speed: Fast access to blockchain data with low latency.

Best crypto APIs for blockchain interactions

Now that we understand the core functionalities of blockchain interaction, let’s explore some of the best crypto APIs available for developers.

RPC providers for blockchain interaction

• Helius: Offers scalable and reliable blockchain RPC services for Solana, Ethereum, and other blockchains.

• Ankr: Provides decentralized RPC nodes for Ethereum, Binance Smart Chain, and more.

• QuickNode: Offers fast and reliable blockchain RPC nodes for various blockchains, including Ethereum, Arbitrum, and Solana.

• Alchemy: One of the most popular providers for Ethereum and other blockchain RPC services, known for its speed and scalability.

• GetBlock: Offers reliable RPC nodes and API services for many blockchains.

• Goldsky: Provides real-time blockchain data indexing, subgraphs, and streaming pipelines to help developers build dApps without managing complex infrastructure.

• OnFinality: A blockchain infrastructure platform offering scalable API endpoints and one-click solutions for deploying, monitoring, and scaling blockchain nodes across major networks.

• Triton: Delivers low-latency RPC solutions and scalable infrastructure for Web3 and DeFi applications, supporting decentralized apps with reliable data processing.

• Dwellir: Specializes in providing robust blockchain node infrastructure and RPC services for Polkadot and Kusama ecosystems, ensuring high availability and low latency.

Price feeds and market data APIs

• Token Metrics: Provides price, market cap, and other key metrics for cryptocurrencies.

• CoinMarketCap: A popular source for real-time cryptocurrency data, including prices, market caps, and volume.

• CoinGecko: Another trusted provider of real-time market data for cryptocurrencies.

• 0xMatcha: A price aggregator focused on DeFi tokens.

• Glassnode: A blockchain analytics platform that provides on-chain and financial metrics, offering actionable insights into digital asset markets.

NFT data APIs

• OpenSea: Offers API access to NFT data, including metadata, ownership records, and trading information.

• NFTPort: Provides access to NFT data from various blockchains and platforms.

Payments and off-ramps

• Loop Crypto: A payment API for handling crypto transactions with seamless implementation for merchants and a range of integrations into traditional payment platforms.

• Fern HQ: Provides tools for Web3 developers to build and manage decentralized applications with a focus on simplifying infrastructure.

• Beam: Specializes in Web3 payments, offering off-ramp solutions for crypto payouts with bank-grade compliance and fiat liquidity.

• Bridge.xyz: Builds a stablecoin-based payments platform that simplifies global money movement through APIs for seamless dollar conversions.

How to choose the best crypto API for your needs

When selecting the best API for your blockchain interactions, consider the following:

• What problem are you trying to solve? Different APIs offer different services, so choose one that meets your specific needs.

• Reliability: Check the provider’s uptime and historical performance.

• Accuracy of Data: Ensure the API provides accurate and up-to-date data.

• Pricing: Consider the cost of the API, especially if you plan to scale.

• Breadth of Information: Look for APIs that support multiple blockchains and tokens.

• Speed: Fast responses are crucial for real-time applications.

Conclusion

Interacting with blockchains is an essential part of many crypto applications, whether you're building wallets, explorers, DeFi apps, or NFT platforms. Using APIs and RPCs simplifies the complex process of reading from and writing to a blockchain, enabling developers to focus on creating innovative solutions without worrying about the underlying infrastructure.

By selecting the right API provider and understanding your needs, you can ensure that your application is efficient, secure, and scalable. Whether you're querying transaction data, interacting with smart contracts, or fetching market prices, there’s an API out there to help you streamline your blockchain development.

Happy coding!

FAQs

What is a crypto API and how does it work?

A crypto API is a set of protocols and tools that allow developers to interact with cryptocurrency networks programmatically. It enables access to blockchain data, market information, and secure transaction execution, simplifying the integration of blockchain functionality into applications.

How do I integrate a crypto API into my application?

To integrate a crypto API, you typically register for an API key, review the API documentation, and use the provided endpoints in your application code. This often involves making HTTP requests to retrieve or send data, such as querying blockchain events or executing transactions.

What types of data can I access with a crypto API (e.g., market data, blockchain events, transaction history)?

Crypto APIs provide access to various data types, including real-time and historical market prices, blockchain transaction details, wallet balances, smart contract events, and network statistics. Some APIs also support advanced features like analytics and custom event monitoring.

What are the differences between public and private APIs in cryptocurrency platforms?

Public APIs are open to all users and provide general data like market prices or blockchain stats without requiring authentication. Private APIs require authentication (e.g., API keys) and offer personalized or sensitive data access, such as account balances or transaction management.

How can I monitor blockchain events using APIs (e.g., webhooks or notifications)?

Blockchain events can be monitored using webhooks, which send real-time notifications to a specified endpoint when specific events occur (e.g., a transaction confirmation). This is more efficient than polling since it uses a push model to automatically deliver updates.

What are the pricing models for popular crypto APIs?

Crypto APIs often use tiered pricing models based on usage limits, with free tiers offering basic features and paid tiers providing higher limits and advanced functionalities. Pricing may vary depending on factors like the number of API calls, data types accessed, and additional services like analytics or support.