Arbitrum Local Development Compatibility Project

Project Overview

Goal: Local testing patch that adds native support for Arbitrum precompiles (ArbSys at 0x64, ArbGasInfo at 0x6c) and transaction type 0x7e (deposits) to Hardhat and Foundry (Anvil).

Why: Today, Hardhat/Anvil can't call Arbitrum precompiles or parse 0x7e; devs must deploy to testnet to validate core flows.


True Local Development for Arbitrum

If you've built on Arbitrum, you know the challenge, your local development environment doesn't understand its unique on-chain features.

Standard tools like Hardhat and Foundry can't natively handle Arbitrum-specific precompiles or transaction types, forcing a difficult choice:

Either write inaccurate mocks or constantly deploy to a live testnet for basic validation.

This friction slows down innovation and adds complexity to your workflow.


The Arbitrum Local Dev Patch Solves This

We have built a lightweight, easy-to-install patch that brings native support for Arbitrum's core functionalities directly into your local Hardhat and Foundry environments.

This tool closes the gap between local testing and on-chain execution, allowing you to build, test, and iterate with confidence.


Key Features

1. Test with High Fidelity

Stop mocking and start emulating. Our patch adds native support for Arbitrum’s most critical precompiles, allowing your smart contracts to interact with them just as they would on mainnet.

  • ArbSys (0x...64) — Test logic that relies on arbChainID(), arbBlockNumber(), and other system-level information.
  • ArbGasInfo (0x...6c) — Validate custom gas logic by calling functions like getL1BaseFeeEstimate() directly in your unit tests.

2. Simulate Cross-Chain Interactions

Confidently test applications that rely on L1-to-L2 messaging. The patch extends local testnets to parse, decode, and execute Arbitrum’s unique deposit transactions (0x7e).

This enables end-to-end local testing for:

  • Retryable tickets
  • L1-initiated contract deployments and calls
  • Any system that depends on bridging assets or data

3. Accelerate Your Workflow

Instead of waiting minutes for a testnet deployment to validate a single change, get instant feedback from your local test suite.

By enabling true local unit testing for Arbitrum-specific features, our patch:

  • Dramatically speeds up development cycles
  • Reduces debugging time
  • Improves iteration efficiency

Who Is This For?

This tool is designed for any developer building within the Arbitrum ecosystem, including:

  • Teams on Arbitrum One, Nova, and Stylus
  • Developers working with cross-chain messaging or retryable tickets
  • Projects implementing custom gas logic
  • Frameworks and dApps building on the Orbit appchain stack

Available Tools

Our solution is delivered as two distinct packages to integrate with your preferred development environment:

Hardhat Patch — @arbitrum/hardhat-patch

Plugin architecture with EVM extension

  • A simple npm package that extends the Hardhat Network to support Arbitrum precompiles and the 0x7e transaction type.

Anvil Fork — anvil-arbitrum

  • A custom fork of Anvil that embeds the same powerful emulation features, activated with a simple --arbitrum flag. It works as a drop-in replacement for the standard anvil binary.

Foundry -

  • revm precompile extension with transaction type support

Running the Probes

Hardhat Probes

BASH
# Navigate to a Hardhat project
cd your-hardhat-project

# Run individual probes
npx hardhat run probes/hardhat/test-arbsys-calls.js
npx hardhat run probes/hardhat/test-arbgasinfo.js
npx hardhat run probes/hardhat/test-deposit-tx.js

Foundry Probes

BASH
# Navigate to a Foundry project
cd your-foundry-project

# Run Solidity tests
forge test --match-contract ArbitrumPrecompileTest -vvv

# Run shell script (requires jq and curl)
chmod +x probes/foundry/test-deposit-flow.sh
./probes/foundry/test-deposit-flow.sh

Dependencies

  • Hardhat: JavaScript-based EVM with plugin architecture
  • Foundry: Rust-based revm with performance focus
  • Arbitrum: Layer 2 scaling solution with custom precompiles

Notes

  • All findings are based on current state analysis
  • Implementation complexity estimates are preliminary
  • Probe files provide validation capabilities for future development
  • Design brief is ready for engineering team implementation
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