Blockchain APIs

Blockchain and cryptocurrency APIs

10 APIs in this category · last checked 2 October 2026
10
APIs listed
4
need no API key (40%)
0
CORS enabled (0%)
10
HTTPS (100%)

This directory lists 10 blockchain APIs. Use the filters below to narrow by authentication, HTTPS support and CORS. Every entry shows whether it needs authentication, serves over HTTPS and allows cross-origin requests, so you can pick one that fits your stack before you read a single doc page.

Showing 10 of 10 APIs

Nownodes

Blockchain as a service giving JSON RPC, gRPC and WebSocket access to more than 120 networks including Bitcoin, Ethereum and Solana, with a free plan covering 100,000 monthly requests.

Auth: apiKey HTTPS CORS: Unknown

Steem

Developer portal for the Steem blockchain social network covering account management, transaction broadcasting and market history, with tutorials in JavaScript, Python and Ruby.

Auth: No HTTPS CORS: Unknown

Watchdata

Raw and structured data from Ethereum, Tron, Binance Smart Chain, Bitcoin and Polygon through a key based API that the docs claim takes about a minute to integrate.

Auth: apiKey HTTPS CORS: Unknown

The Graph

Decentralized protocol for querying indexed blockchain data with GraphQL through subgraphs or Substreams, covering more than 60 networks without running your own indexer.

Auth: apiKey HTTPS CORS: Unknown

Chainpoint

Open standard and gateway service for anchoring arbitrary data to the Bitcoin blockchain to produce a verifiable timestamp proof, with a CLI and JavaScript client on GitHub.

Auth: No HTTPS CORS: Unknown

Chainlink

Developer hub for Chainlink oracle networks covering price Data Feeds, Automation, Functions and the Cross Chain Interoperability Protocol, with tutorials and a local simulator.

Auth: No HTTPS CORS: Unknown

Bitquery

GraphQL and WebSocket access to historical and real time data across more than 40 blockchains, including DEX trades, transfers and token prices, authenticated with a bearer token.

Auth: apiKey HTTPS CORS: Unknown

Etherscan

Same blockchain data that powers Etherscan's block explorers, covering balances, transactions, logs and contract source code across 60 plus EVM chains under one API key.

Auth: apiKey HTTPS CORS: Unknown

Helium

Entity API and third party providers give access to Helium network data for its LoRaWAN IoT and Wi-Fi offload networks, which migrated from Helium's own blockchain to Solana in 2023.

Auth: No HTTPS CORS: Unknown

Covalent

Covalent's API now operates as GoldRush, covering balances, transactions, token prices and decoded logs across more than 100 chains, with a free trial and plans from 10 dollars a month.

Auth: apiKey HTTPS CORS: Unknown

Best Blockchain APIs for Developers

A blockchain API allows developers to read on-chain data, broadcast transactions, query smart contracts, and interact with decentralized networks without running a full node. These APIs abstract away the complexity of peer-to-peer blockchain protocols.

For raw chain data without running your own node, Etherscan and NOWNodes are the fastest starting points: Etherscan covers 60 or more EVM chains under one API key, while NOWNodes adds Bitcoin, Solana and dozens of other networks with a 100,000 request free plan.

For indexed, queryable data, The Graph and Bitquery expose GraphQL endpoints over subgraphs and 40 plus chains, saving you from building your own indexer, while Chainlink suits teams that need price feeds and oracles inside smart contracts rather than off chain lookups. The main pitfall in this category is churn: providers rebrand, change pricing, or quietly shut down, so confirm a service is still maintained before building on it in production.

What to check before you pick one

  • Chain support: Ensure the API supports all the networks your dApp targets, such as Ethereum, Polygon, or Solana.
  • Websocket support: Real-time subscriptions to new blocks and events are essential for live dashboards.
  • Archive node access: For querying historical state, you need an API backed by an archive node, not just a full node.

Frequently Asked Questions

What are blockchain APIs?

Blockchain APIs provide programmatic access to on-chain data including transaction history, wallet balances, smart contract interactions, NFT metadata, and DeFi protocol data across networks like Ethereum and Bitcoin.

Do I need an API key to query blockchain data?

Some blockchain APIs like Etherscan and Infura require free API keys. Others, such as public Ethereum JSON-RPC endpoints, allow anonymous queries with rate limits.

What can I build with a blockchain API?

You can build crypto portfolio trackers, NFT marketplaces, DeFi dashboards, blockchain explorers, and Web3 wallets using the APIs in this directory.

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