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Ethereum smart contract audit and development

What building and auditing smart contracts on Ethereum involves: the EVM, Solidity and Vyper, common tooling, key risk areas and how to prepare.

Ethereum is the reference smart contract platform: a proof-of-stake blockchain whose execution environment, the Ethereum Virtual Machine (EVM), has been adopted by many other networks. Building on Ethereum gives a project the deepest pool of tooling, libraries and experienced reviewers, but also exposes it to an adversarial environment where every transaction is public and value on mainnet attracts sophisticated attackers.

Building on Ethereum

Contracts are compiled to EVM bytecode and run in an account-based model: each contract has its own storage, and every state change costs gas paid by the caller. Solidity is the dominant language, with Vyper as a smaller alternative focused on simplicity. Deployed code is immutable unless the project adopts an upgradeable proxy pattern, which adds its own governance and storage layout questions.

Languages: Solidity, Vyper
Frameworks: Foundry, Hardhat
Common building blocks: audited standard libraries for tokens (ERC-20, ERC-721, ERC-1155), access control and proxies

What auditors look at

Reentrancy and the order of external calls versus state updates, including through token callbacks
Access control on privileged functions, ownership transfer, multisig and timelock configuration
Oracle usage and price manipulation, especially where flash loans can move a market within one transaction
Front-running and MEV exposure: slippage limits, deadlines, commit and reveal where ordering matters
Upgradeable proxies: initializer protection, storage layout collisions and who can trigger an upgrade

Before requesting quotes

Freeze a commit hash and share the list of files in scope, with the nSLOC count if you have it
Document the intended roles, privileged actions and trust assumptions (admin keys, oracles, external protocols)
Provide a working Foundry or Hardhat test suite, ideally with fuzzing or invariant tests on core accounting
State which networks you will deploy to, since the same code may later run on other EVM chains

Ethereum smart contract auditors

4soft
Public informationPoland
Wrocław software house for blockchain development, on-chain analytics and crypto compliance
- Development
- Audit
Ethereum · Arbitrum · Base · Polygon · BNB Chain · +4 more
ABDK Consulting
Public information
Audits of smart contracts, ZK circuits and cryptographic schemes, plus research and consulting
- Audit
Ethereum · Starknet
Ackee Blockchain Security
Public informationCzechia
Prague firm auditing Solana and EVM smart contracts, maker of the Wake and Trident fuzzers
- Audit
Ethereum · Solana
Adevar Labs
Public informationUnited States
Blockchain security firm offering audits, fuzzing, formal verification and penetration testing
- Audit
- Penetration testing
Solana · Ethereum · Sui · Aptos · BNB Chain
Blaize
Public informationUkraine
Ukrainian blockchain development company with a dedicated security audit practice
- Development
- Audit
Ethereum · Polygon · Arbitrum · Solana · Sui · +4 more
BlockSec
Public information
Web3 security company offering smart contract and infrastructure audits plus threat monitoring
- Audit
Ethereum · Arbitrum · BNB Chain · Sui
CertiK
Public informationUnited States
Web3 security firm offering manual smart contract audits, formal verification and pentests
- Audit
- Penetration testing
Ethereum · BNB Chain · Polygon · TON · Cosmos
Certora
Public information
Smart contract audits combining manual review with formal verification by Certora Prover
- Audit
Ethereum · Solana · Sui
Chainscore Labs
Public informationIndia
Pune blockchain engineering studio building DeFi protocols, wallets and node clients
- Development
- Audit
Ethereum · Arbitrum · Base · Polygon · Polkadot
ChainSecurity
Public informationSwitzerland
Zurich smart contract audit firm reviewing DeFi, stablecoin, bridge and L1/L2 code
- Audit
Ethereum · Solana · Starknet · Sui · Aptos
CoinFabrik
Public informationArgentina
Argentine blockchain security and development company auditing Solidity, Rust, Clarity and Soroban
- Development
- Audit
Ethereum · Solana · Polkadot
Coinspect
Public information
Web3 security firm: smart contract, L1/L2 protocol and source code audits, penetration testing
- Audit
- Penetration testing
Ethereum · BNB Chain · Polygon · Optimism · ZKsync · +2 more
Composable Security
Public informationPoland
Kraków firm auditing EVM smart contracts, off-chain components and AI integrations
- Audit
Ethereum · Base · BNB Chain
CredShields
Public informationSingapore
Security firm offering manual smart contract audits, pentesting and the SolidityScan scanner
- Audit
- Penetration testing
Ethereum · Solana
Cyfrin
Public information
Smart contract audits, penetration testing and security education, maker of Aderyn and Solodit
- Audit
- Penetration testing
Ethereum · ZKsync · Arbitrum · Avalanche · BNB Chain · +8 more
Dedaub
Public informationMalta
Smart contract audits and the Dedaub Security Suite, with an EVM decompiler and monitoring
- Audit
Ethereum
Ethereal Labs
Public informationUnited Kingdom
London onchain development studio building smart contracts, dApps, token and NFT launches
- Development
- Audit
Ethereum · Base · Solana · Polygon · Avalanche
Functori
Public informationFrance
French deep-tech firm building blockchain protocols, smart contracts and dApps, with formal methods
- Development
- Audit
Ethereum
FuzzingLabs
Public informationFrance
French offensive security company auditing blockchains and smart contracts with fuzzing
- Audit
Solana · Ethereum · NEAR · Starknet · Sui · +3 more
Guardian
Public information
Smart contract audits with invariant fuzzing, plus off-chain pentests and SDK audits
- Audit
- Penetration testing
Ethereum · Solana
Hacken
Public informationEstonia
Estonian blockchain security and compliance firm: audits, pentests and MiCA, DORA readiness
- Audit
- Penetration testing
Ethereum · Solana · Sui
Halborn
Public information
Blockchain security firm: smart contract assessments, L1 reviews, penetration testing, advisory
- Audit
- Penetration testing
Ethereum · Solana · Cosmos
Hexens
Public informationUnited Kingdom
Offensive security firm auditing smart contracts, L1/L2 protocols, ZK and cryptography
- Audit
- Penetration testing
Ethereum · Polygon · ZKsync · Aptos
INC4
Public informationUkraine
Kyiv engineering studio whose Blockchain Hub builds L1s, DeFi protocols and smart contracts
- Development
- Audit
Ethereum · Base · Arbitrum · BNB Chain · Polygon · +1 more
iosiro
Public informationSouth Africa
South African security firm offering smart contract audits, penetration testing and threat modeling
- Audit
- Penetration testing
Ethereum · Arbitrum
Least Authority
Public informationGermany
Berlin security consultancy auditing smart contracts, cryptographic protocols and ZK systems
- Audit
Ethereum · Polygon · Cosmos · Solana · Avalanche
Macro
Public information
Boutique firm auditing smart contracts and Solana programs, with protocol development
- Audit
- Development
Ethereum · Solana · Optimism · Arbitrum · Base
Metlabs
Public informationSpain
Spanish blockchain-only development company focused on RWA tokenization and smart contracts
- Development
- Audit
Ethereum · Polygon · BNB Chain · Arbitrum · Solana
MixBytes
Public informationCayman Islands
DeFi-focused audit firm: design reviews, smart contract audits and ongoing security support
- Audit
Ethereum · Solana
Neodyme
Public informationGermany
German security firm auditing Solana programs and core blockchains, with pentests and trainings
- Audit
- Penetration testing
Solana · Ethereum
Nethermind
Public informationUnited Kingdom
London blockchain engineering and research firm; its Nethermind Security arm audits smart contracts
- Development
- Audit
Ethereum · Starknet · ZKsync · Solana
Oak Security
Public informationGermany
Munich-based Web3 security firm auditing EVM, Solana, Cosmos, Substrate and Starknet code
- Audit
- Penetration testing
Ethereum · Solana · Cosmos · Polkadot · Starknet · +2 more
Omniscia
Public informationBulgaria
Blockchain security firm auditing Solidity smart contracts, with web-based public reports
- Audit
Ethereum · Polygon · Arbitrum · Base · BNB Chain · +3 more
OpenZeppelin
Public informationUnited Kingdom
Smart contract security audits and the open-source OpenZeppelin Contracts library
- Audit
Ethereum · Arbitrum · Optimism · Base · ZKsync · +2 more
OtterSec
Public information
Blockchain security firm auditing layer 1s, wallets, DeFi and bridges, with pentesting and fuzzing
- Audit
- Penetration testing
Solana · Ethereum · Sui · Aptos · Cosmos · +1 more
Pashov Audit Group
Public information
Remote team of security researchers auditing EVM, Solana and Move smart contracts
- Audit
Ethereum · Solana · Arbitrum · Optimism · Base · +3 more
PeckShield
Public information
Blockchain security company auditing smart contracts, blockchains and digital wallets
- Audit
Ethereum
Pessimistic
Public informationEstonia
Tallinn audit firm reviewing Ethereum smart contracts, dApps and protocols, maker of Slitherin
- Audit
Ethereum
Protofire
Public information
Blockchain engineering firm building and auditing smart contracts on EVM chains, Solana and Cardano
- Development
- Audit
Ethereum · Solana · Cardano
Quantstamp
Public information
Web3 security firm offering smart contract audits, economic analysis and infrastructure tests
- Audit
- Penetration testing
Ethereum · Solana · Polygon · TON · Avalanche · +3 more
QuillAudits
Public information
Smart contract audit firm also offering dApp penetration testing, wallet audits and monitoring
- Audit
- Penetration testing
Ethereum · NEAR · BNB Chain · Polygon · Optimism · +8 more
Rather Labs
Public informationUnited States
Web3 and AI engineering firm with a Buenos Aires team, building and auditing smart contracts
- Development
- Audit
Ethereum · Arbitrum · Base · Optimism · Polygon · +5 more
Runtime Verification
Public information
Formal methods firm offering security audits, fuzzing and formal verification
- Audit
Ethereum · Solana
Salus
Public information
Web3 security firm offering smart contract audits, penetration testing and zero-knowledge services
- Audit
- Penetration testing
Ethereum · BNB Chain · Polygon · Arbitrum · Avalanche
ScaleBit
Public information
Web3 security team auditing smart contracts, dApps and blockchains, with a Bitcoin layer 2 focus
- Audit
Ethereum · Arbitrum · BNB Chain · Solana · Polygon · +3 more
Security Research Labs
Public informationGermany
Berlin security research firm reviewing smart contracts, chain runtimes and bridges
- Audit
- Penetration testing
Ethereum · Cosmos · Solana · Polkadot
Shieldify
Public informationBulgaria
Bulgarian Web3 security company offering smart contract audits by review or by subscription
- Audit
- Penetration testing
- Development
Ethereum · Solana · ZKsync · Avalanche · BNB Chain · +1 more
Sigma Prime
Public informationAustralia
Blockchain security audits and Ethereum infrastructure engineering, maker of Lighthouse
- Audit
Ethereum
SlowMist
Public informationChina
Blockchain threat intelligence firm auditing exchanges, wallets, blockchains and smart contracts
- Audit
Ethereum · TON
softstack
Public informationGermany
Flensburg Web3 company offering smart contract audits, pentests, development and compliance
- Development
- Audit
- Penetration testing
Ethereum · Arbitrum · Optimism · Base · Polygon · +8 more
Statemind
Public information
Audit firm specialised in Solidity and Vyper DeFi code, with Vyper compiler fuzzing research
- Audit
Ethereum
Three Sigma
Public information
Code security audits and economic audits for Web3 protocols, in Solidity, Rust and Move
- Audit
Ethereum · Arbitrum · Polygon · Base · Optimism · +4 more
Trail of Bits
Public informationUnited States
Security firm reviewing smart contracts, nodes and bridges, maker of Slither and Echidna
- Audit
- Penetration testing
Ethereum · Arbitrum · Optimism · Solana · Sui · +4 more
Verichains
Public informationVietnam
Security firm auditing smart contracts, protocols and cryptography, with penetration testing
- Audit
- Penetration testing
Ethereum · BNB Chain · Solana · Avalanche · Polygon · +1 more
Veridise
Public information
Smart contract and zero-knowledge audits backed by formal methods and in-house tools
- Audit
Ethereum · Arbitrum · Optimism · Base · Polygon
Xcapit
Public informationArgentina
Argentine software company building and auditing smart contracts, with pentesting services
- Development
- Audit
- Penetration testing
Ethereum · Polygon
Zealynx
Public informationPoland
Polish security firm offering smart contract audits, dApp pentesting and AI security reviews
- Audit
- Penetration testing
- Development
Ethereum · Arbitrum · Polygon · BNB Chain · Base · +4 more
Zellic
Public information
Security assessments of smart contracts, ZK circuits, L1s and web applications
- Audit
- Penetration testing
Ethereum · Solana · Aptos · Sui · Cosmos
Zokyo
Public informationUnited Arab Emirates
Smart contract and protocol audits, pentesting, compliance and product development, Dubai
- Audit
- Penetration testing
- Development
Ethereum · Solana · Polygon · Arbitrum · Optimism · +9 more

Ethereum smart contract developers

4soft
Public informationPoland
Wrocław software house for blockchain development, on-chain analytics and crypto compliance
- Development
- Audit
Ethereum · Arbitrum · Base · Polygon · BNB Chain · +4 more
Blaize
Public informationUkraine
Ukrainian blockchain development company with a dedicated security audit practice
- Development
- Audit
Ethereum · Polygon · Arbitrum · Solana · Sui · +4 more
BootNode
Public information
Web3 development consultancy building smart contracts, dApps and infrastructure for Ethereum teams
- Development
Ethereum · Optimism · ZKsync
ChainSafe
Public information
Open-source blockchain R&D firm offering protocol engineering, infrastructure and co-development
- Development
Ethereum · Polkadot · Optimism
Chainscore Labs
Public informationIndia
Pune blockchain engineering studio building DeFi protocols, wallets and node clients
- Development
- Audit
Ethereum · Arbitrum · Base · Polygon · Polkadot
CoinFabrik
Public informationArgentina
Argentine blockchain security and development company auditing Solidity, Rust, Clarity and Soroban
- Development
- Audit
Ethereum · Solana · Polkadot
dOrg
Public informationUnited States
US-registered Web3 development cooperative building smart contracts, DeFi and DAO tooling
- Development
Ethereum · Starknet
Ethereal Labs
Public informationUnited Kingdom
London onchain development studio building smart contracts, dApps, token and NFT launches
- Development
- Audit
Ethereum · Base · Solana · Polygon · Avalanche
Functori
Public informationFrance
French deep-tech firm building blockchain protocols, smart contracts and dApps, with formal methods
- Development
- Audit
Ethereum
INC4
Public informationUkraine
Kyiv engineering studio whose Blockchain Hub builds L1s, DeFi protocols and smart contracts
- Development
- Audit
Ethereum · Base · Arbitrum · BNB Chain · Polygon · +1 more
Labrys
Public informationAustralia
Brisbane product studio building smart contracts, DeFi protocols and full Web3 products
- Development
Ethereum · Base · Arbitrum · Optimism · Polygon · +1 more
LambdaClass
Public information
Engineering firm building zero-knowledge systems, Ethereum clients and verified blockchain software
- Development
Ethereum · Starknet
Lampros Tech
Public informationIndia
Ahmedabad engineering firm building Ethereum and Layer 2 smart contracts, dApps and DAO tooling
- Development
Ethereum · Arbitrum · Optimism · Base
LimeChain
Public informationBulgaria
Bulgarian blockchain engineering firm building smart contracts, protocols and onchain products
- Development
Ethereum · Polygon · Base · Solana · NEAR · +1 more
Linum Labs
Public informationSwitzerland
Swiss blockchain software studio building Web3 and fintech products on EVM, HyperEVM and Solana
- Development
Ethereum · Solana
Macro
Public information
Boutique firm auditing smart contracts and Solana programs, with protocol development
- Audit
- Development
Ethereum · Solana · Optimism · Arbitrum · Base
Metlabs
Public informationSpain
Spanish blockchain-only development company focused on RWA tokenization and smart contracts
- Development
- Audit
Ethereum · Polygon · BNB Chain · Arbitrum · Solana
Moonsong Labs
Public informationUnited States
Blockchain engineering firm for institutional protocols, tokenization and payment infrastructure
- Development
Ethereum · ZKsync · Solana · Polkadot
Nethermind
Public informationUnited Kingdom
London blockchain engineering and research firm; its Nethermind Security arm audits smart contracts
- Development
- Audit
Ethereum · Starknet · ZKsync · Solana
Nextrope
Public informationPoland
Polish digital asset infrastructure studio for EVM and XRPL: tokenization, DeFi, stablecoins
- Development
Ethereum
Protofire
Public information
Blockchain engineering firm building and auditing smart contracts on EVM chains, Solana and Cardano
- Development
- Audit
Ethereum · Solana · Cardano
Rather Labs
Public informationUnited States
Web3 and AI engineering firm with a Buenos Aires team, building and auditing smart contracts
- Development
- Audit
Ethereum · Arbitrum · Base · Optimism · Polygon · +5 more
RedDuck
Public informationUkraine
Web3 engineering partner writing audit-ready smart contracts on EVM chains, Solana and Bitcoin
- Development
Ethereum · Polygon · BNB Chain · Arbitrum · Base · +6 more
Rumble Fish
Public informationPoland
Kraków software house with a blockchain practice: smart contracts, DeFi, dApps, bridges
- Development
Ethereum · Solana · Polygon · BNB Chain · Avalanche
ScopeLift
Public information
Crypto engineering consultancy for Solidity smart contracts, dApp frontends and governance tooling
- Development
Ethereum
Shieldify
Public informationBulgaria
Bulgarian Web3 security company offering smart contract audits by review or by subscription
- Audit
- Penetration testing
- Development
Ethereum · Solana · ZKsync · Avalanche · BNB Chain · +1 more
softstack
Public informationGermany
Flensburg Web3 company offering smart contract audits, pentests, development and compliance
- Development
- Audit
- Penetration testing
Ethereum · Arbitrum · Optimism · Base · Polygon · +8 more
Solidity Labs
Public information
Security-first smart contract engineering team that embeds with DeFi and onchain product teams
- Development
Ethereum · Base · Optimism
web3.berlin
Public informationGermany
Berlin Web3 agency for consulting, smart contract and dApp development, and node operations
- Development
Ethereum · Polygon
Xcapit
Public informationArgentina
Argentine software company building and auditing smart contracts, with pentesting services
- Development
- Audit
- Penetration testing
Ethereum · Polygon
Zealynx
Public informationPoland
Polish security firm offering smart contract audits, dApp pentesting and AI security reviews
- Audit
- Penetration testing
- Development
Ethereum · Arbitrum · Polygon · BNB Chain · Base · +4 more
Zokyo
Public informationUnited Arab Emirates
Smart contract and protocol audits, pentesting, compliance and product development, Dubai
- Audit
- Penetration testing
- Development
Ethereum · Solana · Polygon · Arbitrum · Optimism · +9 more
Zpoken
Public informationEstonia
Senior crypto engineering team for L1 consensus, zero-knowledge, DeFi mechanisms and stablecoins
- Development
Ethereum · Solana · NEAR · Arbitrum · Base · +1 more

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