Monad REVM

Monad-revm extends the Revm implementation with Monad-specific customizations.

EVM Compatibility

Component	Version
Revm	v34.0.0
Monad Spec	MONAD_EIGHT (Prague compatible)

Features

Gas Model

Monad uses a modified gas model optimized for its execution environment:

No Gas Refunds — Users pay gas_limit × gas_price, not gas_used × gas_price.

Increased Cold Access Costs — Cold storage reads are more expensive to reflect the cost of state access from disk:

Access Type	Ethereum	Monad
Cold Storage (SLOAD)	2,100	8,100
Cold Account (BALANCE, EXTCODE*, CALL*)	2,600	10,100
Warm Access	100	100

Repriced Precompiles

Several precompiles are repriced to reflect their relative computational cost:

Precompile	Address	Ethereum	Monad	Multiplier
ecRecover	0x01	3,000	6,000	2x
ecAdd	0x06	150	300	2x
ecMul	0x07	6,000	30,000	5x
ecPairing	0x08	45,000 + 34,000/pt	225,000 + 170,000/pt	5x
blake2f	0x09	rounds × 1	rounds × 2	2x
KZG point eval	0x0a	50,000	200,000	4x

Additional Precompiles

Staking Precompile — monad-revm provides read-only access to Monad's native staking state at address 0x1000:

Method	Selector	Gas
getEpoch()	0x757991a8	16,200
getProposerValId()	0xfbacb0be	100
getValidator(uint64)	0x2b6d639a	97,200
getDelegator(uint64,address)	0x573c1ce0	184,900
getWithdrawalRequest(uint64,address,uint8)	0x56fa2045	24,300
getConsensusValidatorSet(uint32)	0xfb29b729	2,100 + 2,100/elem
getSnapshotValidatorSet(uint32)	0xde66a368	2,100 + 2,100/elem
getExecutionValidatorSet(uint32)	0x7cb074df	2,100 + 2,100/elem
getDelegations(address,uint64)	0xa6a7301c	814,000
getDelegators(uint64,address)	0x48e327d0	814,000

Bytecode Limits

Limit	Ethereum	Monad
Max code size	24KB	128KB
Max initcode size	48KB	256KB

Transaction Restrictions

Blob Transactions Rejected — EIP-4844 blob transactions return Eip4844NotSupported.

Installation

Add to your Cargo.toml:

[dependencies]
monad-revm = { git = "https://github.com/category-labs/monad-revm", branch = "main" }

Or from crates.io:

[dependencies]
monad-revm = "0.1"

Usage

Basic Example

use monad_revm::{MonadBuilder, DefaultMonad};
use revm::{
    context::{Context, TxEnv},
    database::InMemoryDB,
    ExecuteEvm,
};

// Create a Monad EVM context
let ctx = Context::monad();
let mut evm = ctx.build_monad();

// Execute a transaction
let tx = TxEnv::builder()
    .caller(caller_address)
    .to(contract_address)
    .value(U256::from(1000))
    .gas_limit(100_000)
    .gas_price(1_000_000_000)
    .build_fill();

let result = evm.transact(tx).expect("Transaction failed");

With Inspector

use monad_revm::{MonadBuilder, DefaultMonad};
use revm::{context::Context, inspector::NoOpInspector};

let ctx = Context::monad();
let mut evm = ctx.build_monad_with_inspector(NoOpInspector {});

With Custom Database

use monad_revm::{MonadBuilder, DefaultMonad};
use revm::context::Context;

let db = MyCustomDatabase::new();
let ctx = Context::monad().with_db(db);
let mut evm = ctx.build_monad();

Architecture

monad-revm/
├── crates/
│   └── monad-revm/
│       └── src/
│           ├── lib.rs           # Re-exports
│           ├── spec.rs          # MonadSpecId hardfork enum
│           ├── cfg.rs           # MonadCfgEnv 
│           ├── handler.rs       # MonadHandler
│           ├── instructions.rs  # Custom gas parameters
│           ├── precompiles.rs   # Repriced precompiles
│           ├── evm.rs           # MonadEvm type alias
│           ├── api/
│           │   ├── builder.rs   # MonadBuilder trait
│           │   ├── exec.rs      # MonadContextTr trait
│           │   └── default_ctx.rs # DefaultMonad extension
│           └── staking/
│               ├── mod.rs       # Staking precompile dispatcher
│               ├── abi.rs       # Gas constants
│               ├── interface.rs # Solidity ABI definitions
│               ├── storage.rs   # Storage slot calculations
│               └── types.rs     # Validator, Delegator, etc.
└── Cargo.toml

Key Components

MonadSpecId — Hardfork identifier. Currently only MonadEight (based on Prague).

MonadHandler — Implements Monad's gas model.

MonadPrecompiles — Provides repriced Ethereum precompiles plus P256VERIFY and the staking precompile.

monad_gas_params() — Returns gas parameters with Monad's cold access costs.

Feature Flags

• serde — Enable serialization for MonadSpecId
• alloy-evm — Enable integration with alloy_evm::precompiles::PrecompilesMap for Foundry/Anvil

Integration with Foundry

See monad-foundry for the complete Foundry integration.

Related Projects

• revm — Base Ethereum Virtual Machine
• alloy-monad-evm — Alloy EVM wrapper for monad-revm
• monad-foundry — Foundry fork with Monad support

References

• Monad Opcode Pricing
• Monad Precompiles
• Monad Changelog

License

Revm is licensed under MIT License.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in these crates by you, shall be licensed as above, without any additional terms or conditions.