Category1free & open source
⛓️

Blockchain

Web3 infrastructure APIs for querying balances and transactions across 20+ chains, reading smart contracts, fetching NFT metadata, tracking DeFi positions, and receiving on-chain webhooks.

10APIs
Most Popular In
Multi-Chain RPCNFT MetadataSmart Contract Interaction
Auth Breakdown
API Key70%
No Auth30%
Notable Developers
AlchemyQuickNodeMoralisInfuraEtherscan
Updated Jun 12, 2026
Curated by FreeAPIHub editors
Topics:Multi-Chain RPCNFT MetadataSmart Contract InteractionDeFi Protocol DataOn-Chain WebhooksBlock Explorer APIs
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⭐Top Resources
Helium Blockchain API logo

Helium Blockchain API

API · Blockchain
Free tierNo Auth

Helium is a decentralized wireless network now running on Solana. Its legacy blockchain API is deprecated; hotspot, reward and token data is read through Solana and public data exports.

5K+ usersNot rated yetView
Etherscan API logo

Etherscan API

API · Blockchain
FreemiumAPI Key

The Etherscan API exposes Ethereum blockchain data from the explorer: account balances, transactions, token transfers, contract ABIs and gas prices as JSON, secured with a free API key.

1000+ usersNot rated yetView
Chainpoint API logo

Chainpoint API

API · Blockchain
Free tierNo Auth

Chainpoint is an open standard for creating blockchain timestamp proofs. You submit a hash of your data, it is anchored to the Bitcoin blockchain, and you receive a proof you can verify independently, forever.

1K+ usersNot rated yetView
The Graph API logo

The Graph API

API · Blockchain
FreemiumAPI Key

The Graph is a decentralized protocol for indexing and querying blockchain data using GraphQL subgraphs, letting dapps read on-chain data without running their own indexers.

12K+ usersNot rated yetView
Alchemy NFT API logo

Alchemy NFT API

API · Blockchain
Free tierAPI Key

The Alchemy NFT API reads NFTs across Ethereum, Polygon and other chains via simple REST calls - owner holdings, token metadata, media and collection data as JSON.

5K+ usersNot rated yetView
Covalent API logo

Covalent API

API · Blockchain
Free tierAPI Key

Covalent is a unified blockchain data API covering many chains through one schema - token balances, transactions, NFTs and historical prices for any address - returned as JSON.

1500+ usersNot rated yetView
Bitquery API logo

Bitquery API

🔥 Hot
Blockchain

Bitquery is a blockchain data platform that queries on-chain activity across many networks - transfers, DEX trades, balances and events - through one GraphQL API with real-time streaming.

FreemiumAPI Key
View details
CoinGecko NFT API logo

CoinGecko NFT API

🔥 Hot
Blockchain

CoinGecko's NFT API returns market data for NFT collections - floor price, market cap, 24h volume and change - across 20+ marketplaces. The free Demo plan covers collection lookups by id.

FreeAPI Key
View details
Web3.js Ethereum API logo

Web3.js Ethereum API

🔥 Hot
Blockchain

web3.js is a JavaScript library for interacting with Ethereum and EVM chains. It talks to a node over JSON-RPC so you can read blocks, query balances, send transactions and call smart contracts from JS.

Free tierNo Auth
View details
MEXC Exchange API logo

MEXC Exchange API

🔥 Hot
Blockchain

The MEXC Exchange API gives developers spot market data and trading on the MEXC crypto exchange - public prices, klines and order books with no key, signed endpoints for trading.

Free tierAPI Key
View details
Showing 10 of 10 resources

At a glance

Compare the top Blockchain APIs

Browse all APIs
APIAccessAuthFormatsRating
Helium Blockchain API logo
Helium Blockchain APIFree tierNo AuthRESTJSON—View
Etherscan API logo
Etherscan APIFreemiumAPI KeyRESTJSON—View
Chainpoint API logo
Chainpoint APIFree tierNo AuthRESTJSON—View
The Graph API logo
The Graph APIFreemiumAPI KeyGraphQLJSON—View
Alchemy NFT API logo
Alchemy NFT APIFree tierAPI KeyRESTJSON—View
Covalent API logo
Covalent APIFree tierAPI KeyRESTJSON—View
Bitquery API logo
Bitquery APIFreemiumAPI KeyGraphQLJSON—View
CoinGecko NFT API logo
CoinGecko NFT APIFreeAPI KeyRESTJSON—View

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About this category

Blockchain — developer guide

What Are Blockchain APIs?

Blockchain APIs bridge the gap between traditional web applications and decentralised infrastructure. Running your own full node for Ethereum, Solana, or Bitcoin is expensive and operationally demanding — a single Ethereum archive node requires 15+ TB of storage and constant maintenance. Blockchain API providers handle all of that, exposing clean JSON-RPC and REST endpoints so you can query on-chain data, submit transactions, and react to contract events without managing any infrastructure.

What Developers Build

  • Multi-chain portfolio trackers showing token balances and transaction history
  • NFT marketplace backends that fetch metadata, ownership history, and floor prices
  • DeFi dashboards aggregating yields, liquidity positions, and protocol risk metrics
  • Blockchain explorer tools with address tagging and contract verification
  • Crypto payment processors that detect on-chain confirmations via webhooks
  • On-chain analytics pipelines feeding data into traditional BI tools

Choosing a Blockchain API Provider

Alchemy supports Ethereum, Base, Arbitrum, Optimism, Polygon, Starknet, and more — known for reliable archive access and the best developer documentation in the space. Moralis and QuickNode offer broader multi-chain coverage including non-EVM chains like Solana and Bitcoin. Infura (ConsenSys) is the long-standing enterprise choice with SLA guarantees. Etherscan provides the most widely integrated block-explorer API for Ethereum-specific transaction and contract data. All offer free tiers with 300M+ compute units/month, sufficient for most development workflows.