Introduction
Arbitrum Reth is a ground-up Rust implementation of Arbitrum Nitro's execution layer. It replaces Nitro's embedded Geth fork with reth, delivering the same state-transition logic through a modular crate architecture.
Each component - ArbOS state management, L1/L2 pricing, precompiles, Stylus WASM execution - lives in its own crate and builds on reth's trait system (BlockExecutor, StateProvider, EvmConfig).
Why Arbitrum Reth?
- Native Rust performance - no CGo boundary, no garbage collector pauses
- Modular by design - each subsystem is an independent crate, consumable as a library
- reth ecosystem - inherits reth's database layer, networking, RPC framework, and CLI
- SDK-ready - build custom Arbitrum tooling, indexers, or alternative node configurations using individual crates
Supported Networks
| Network | Chain ID | Status |
|---|---|---|
| Arbitrum Sepolia | 421614 | Supported |
| Arbitrum One | 42161 | Planned |
How It Works
Arbitrum Reth runs as the execution layer in a two-component architecture:
- Nitro consensus node - handles L1 interaction, sequencer feed, and message ordering
- Arbitrum Reth execution node - executes ordered messages into blocks and manages state
The consensus node drives Arbitrum Reth over the authenticated RPC port (8551) using the nitroexecution_ namespace. The main call is nitroexecution_digestMessage: it delivers one ordered L1-to-L2 message and returns the block Arbitrum Reth produces from it.
License
Arbitrum Reth is licensed under the Business Source License 1.1, consistent with the Arbitrum Nitro license. It converts to Apache 2.0 on December 31, 2030.