Helium

Helium is a global, distributed network of Hotspots that create public, long-range wireless coverage

Official docs outline

Extra Credit builds an outline of Helium's docs the first time your work uses it. Until then, start at the official documentation.

Chainpoint Chainpoint is a global network for anchoring data to the Bitcoin blockchain
ClearTrace Cross-frontend DEX attribution and execution quality data across Ethereum and L2s
Covalent Multi-blockchain data aggregator platform
Dwellir RPC endpoints for 150+ blockchain networks, including Ethereum, Solana, Polkadot and Hyperliquid
Etherscan Ethereum explorer API
Get Started with Web3 Bilingual Web3 lessons, glossary search and role-based learning paths
MELEK Graphene social blockchain (Steem family) with a keyless condenser_api JSON-RPC
Nownodes Blockchain-as-a-service solution that provides high-quality connection via API
Steem Blockchain-based blogging and social media website
SwiftNodes Multi-chain blockchain RPC nodes (Ethereum, Solana and 75+ networks)
The Graph Indexing protocol for querying networks like Ethereum with GraphQL
TWZRD Agent Intel Solana on-chain agent trust scoring via MCP; 4 free tools to score, resolve and verify AI agent wallets