Arbitrum (ARB) API Documentation

Arbitrum

Arbitrum (ARB) is an Ethereum Layer 2 optimistic rollup whose transactions are ordered by a sequencer and whose state claims are secured through fraud-proof validation, with BoLD live on Arbitrum One since February 12, 2025. Contracts use EVM bytecode through Solidity or other EVM languages, while Nitro nodes execute transactions and maintain Ethereum-style account, storage, block, and receipt state. Because Nitro preserves EVM semantics and Ethereum data structures, Arbitrum applications use the same JSON-RPC conventions and tooling common across the EVM ecosystem.

Arbitrum API Methods and Endpoints

NOWNodes exposes Arbitrum's interface, plus a few others, depending on what your integration needs: JSON-RPC for reading chain state and broadcasting transactions, WSS (WebSocket) for real-time subscriptions and events, Blockbook for indexed address, balance, transaction, and block lookups, and Trace/Debug for step-level execution analysis.

Browse the interfaces below for endpoint details, request parameters, response formats, and integration examples. Create an API key, select Mainnet or Testnet, choose the required interface, and start sending requests from your application.

Weighing Arbitrum RPC providers against each other? Read the comparison guide on our blog — this page stays focused on integration reference.