Arbitrum SDK: AI-Optimized Technical Reference

Overview

TypeScript library for cross-chain operations between Ethereum and Arbitrum networks. Version 4.0.4, 38k weekly downloads. Built by Offchain Labs.

Critical Warnings

Breaking Points

• UI fails at 1000 spans: Makes debugging large distributed transactions impossible
• Gas estimation breaks during network congestion: Off by 300% during panic events (USDC depeg March 2023)
• Ethers v5 locked: No ethers v6 support available, requires parallel v5 instances
• Bundle size: Several MB unpacked - consider server-side bridging for size-sensitive apps

Common Failure Modes

• InsufficientValue: L1 transaction lacks ETH for submission cost + gas
• InsufficientSubmissionCost: Wrong submission fee calculation
• DataTooLarge: Transaction data exceeds 117.964 KB limit
• Silent retryable ticket failures: Transactions disappear without clear errors

Configuration That Works in Production

Installation

npm install @arbitrum/sdk

Requirements: Node.js 16+, ethers v5 only

Webpack 5 Polyfills (Required)

// webpack.config.js - prevents "Can't resolve 'crypto'" errors
module.exports = {
  resolve: {
    fallback: {
      "stream": require.resolve("stream-browserify"),
      "crypto": require.resolve("crypto-browserify")
    }
  }
}

Network Setup

import { getArbitrumNetwork, registerCustomArbitrumNetwork } from '@arbitrum/sdk'

// Standard networks auto-configure
const arbNetwork = await getArbitrumNetwork(42161) // Arbitrum One

// Custom Orbit chains require exact parameters
await registerCustomArbitrumNetwork({
  chainID: 123456,
  parentChainID: 1,
  // Get these from Orbit deployment logs - wrong addresses = transactions vanish
  ethBridge: "0x...",
  tokenBridge: "0x..."
})

Resource Requirements

Time Investments

• Local testnet setup: 30 minutes (following docs exactly) vs 3 hours (Docker networking issues)
• SDK v3→v4 migration: 1 week for custom gateway configs
• Production debugging: 2+ days for React Native crypto polyfills

Gas & Timing

• Parent→Child messages: 10-15 minutes normal, hours during congestion
• Child→Parent withdrawals: 7 days (Arbitrum One/Nova challenge period)
• Manual gas limits required: Automatic estimation fails during network spikes

Bundle Impact

• Standard bridging: 2-3MB after tree-shaking
• Full SDK: Several MB unpacked
• Alternative: Server-side bridging for size-critical apps

Decision Criteria

When to Use Arbitrum SDK

• Cross-chain operations required: Essential for retryable tickets, fraud proofs
• TypeScript project: Full type safety vs manual interface definition
• Standard tokens: Auto-detects gateway configurations
• Production DeFi: Battle-tested by protocols handling billions TVL

When to Avoid

• Bundle size critical: Consider backend implementation
• Ethers v6 required: SDK locked to v5
• Simple read operations: JSON-RPC sufficient
• Non-Arbitrum chains: SDK Arbitrum-specific

Alternatives Comparison

Solution	Type Safety	Gas Estimation	Maintenance	Learning Curve
Arbitrum SDK	Full TypeScript	Automatic + buffers	Offchain Labs	Moderate
Direct contracts	Manual interfaces	Manual calculation	Self-maintained	High
Custom bridge	Custom implementation	Custom logic	Self-maintained	Very high

Architecture Components

Bridger Classes

• EthBridger: Native ETH transfers, gas estimation quirks during spikes
• Erc20Bridger: Token transfers via gateway system, weird tokens cause issues
• EthL1L3Bridger/Erc20L1L3Bridger: Skip L2 hop, saves fees but complex failure modes

Message Lifecycle

// Parent→Child: Usually works, can stall during congestion
const parentToChild = new ParentToChildMessage(...)
await parentToChild.waitForStatus()

// Child→Parent: 7-day withdrawal period
const childToParent = new ChildToParentMessage(...)
await childToParent.waitForStatus() // Track progress
await childToParent.execute() // Final execution after challenge period

Utility Modules

• EventFetcher: Handles massive Arbitrum event logs
• MultiCaller: Batch RPC calls to avoid rate limits
• Constants: Hardcoded addresses, updated with protocol upgrades

Debugging Strategies

Enable Debug Logging

DEBUG=arbitrum:* node your-app.js

Transaction Tracing

1. Etherscan VM trace: Get actual error signatures
2. sig.eth.samczsun.com: Decode error signatures
3. Tenderly: Smart contract debugging tools
4. Arbiscan blocks: Check network congestion

Common Error Patterns

// Always set manual gas limits in production
const tx = await ethBridger.deposit({
  amount: ethAmount,
  parentSigner: l1Signer,
  childProvider: l2Provider,
  overrides: {
    gasLimit: 150000 // Manual limit prevents estimation failures
  }
})

Network Support

• Arbitrum One: Production mainnet
• Arbitrum Nova: Lower-cost option
• Arbitrum Sepolia: Testnet - always test here first
• Orbit chains: Custom configs via registerCustomArbitrumNetwork

Migration Notes (v3→v4)

• Simplified bridger APIs
• Breaking changes in custom gateway handling
• Enhanced TypeScript support
• Budget extra time for custom token configurations

Support Resources

• 38k weekly downloads: Active community finds bugs quickly
• Offchain Labs maintained: Regular updates for protocol changes
• Discord/Forum: Technical support available
• Comprehensive documentation: API references and tutorials

Production Checklist

• Test on Sepolia testnet first
• Manual gas limits configured
• Debug logging enabled
• Webpack polyfills added (if applicable)
• Latest SDK version installed
• Custom network parameters verified (Orbit chains)
• Error handling for retryable ticket failures
• User education about withdrawal delays