We’ve tested and found the best smart contract auditing and security tools that every web3 smart contract developer should include in their stack.
According to Chainalysis, $2.2 billion was stolen from crypto platforms in 2024. This is over 20 percent higher than the losses in 2023.
Building a more robust and reliable web3 ecosystem is hard work. A big part of getting there is ensuring developers have the tools to build secure smart contracts.
However, prioritizing the security of your codebase as a smart contract engineer and performing security reviews can be a long and difficult task.
That’s why we’ve compiled a list of the top eight smart contract auditing and security tools our auditors think every smart contract developer should include in their stack.
Fuzz testing is necessary for any blockchain project, and auditors must know how to perform it correctly.
Echidna is a smart contract security tool that uses property-based fuzzing to discover vulnerabilities by testing contracts against user-defined predicates.
Developed by Trail of Bits, Echidna is known for its flexibility and comprehensive toolset, which enable it to break the most difficult assertions. It’s an ideal choice for developers to run fuzz tests while ensuring the robustness and security of their contracts.
Price: Free
Key features
However, the Trail of Bits team didn’t stop at Echidna and developed another tool in our list of top smart contract security auditing tools: Medusa
Medusa is an experimental smart cross-platform go-ethereum-based smart contract fuzzer inspired by Echidna.
It enables parallelized fuzz testing of smart contracts through a command-line interface (CLI) or its Go Application Programming Interface (API), offering the flexibility to implement custom, user-defined testing methods.
Although Medusa couldn’t make it to the first position of our top smart contract auditing tools list, it revealed itself as one of the most powerful publicly available smart contract fuzzers.
Price: Free
Key features
Diligence Fuzzing is another smart contract fuzz testing tool that couldn’t be missed on our list.
Built by Consensys, Diligence Fuzzing offers a fully-fledged smart contract fuzzing as a service platform powered by Harvey. Harvey is a powerful fuzzer for Ethereum’s bytecode that delves deep into the contract codes, mutating and testing various inputs to identify potential issues.
Price: From 0 to $1,999
Key features
If you want a cloud-based alternative, Recon offers invariant testing as a service. Invariant testing is a specific form of fuzzing that tests whether certain fundamental properties (invariants) hold under all conditions.
Recon integrates Echidna, Medusa, Foundry, and more into one platform. It enables parallel fuzzing, reusable test setups, and live monitoring, helping projects like Centrifuge and Badger DAO secure over $1B+ in TVL.
On top of that, Recon’s free Builder lets open-source projects set up Medusa and Echidna invariant testing in just two clicks, with seamless Foundry integration and zero setup.
Static analyzers are another type of smart contract security auditing tool. Unit and fuzz testing is known as dynamic testing. Dynamic means that you’re doing something, like actually running our code.
Smart contract static analyzers, instead, just look at our code. They don’t run it but try to find logic issues or other potential vulnerabilities.
Cyfrin’s dedication to advancing smart contract security has created Aderyn - an open-source, Rust-based, static analyzer able to detect and report suspected vulnerabilities in Solidity smart contracts. The tool traverses the Abstract Syntax Trees (AST) and identifies potential issues.
Aderyn automatically analyzes a smart contract’s codebase and quickly finds possible threats, reporting them in an easy-to-digest markdown format. It also allows developers to build their own detectors through Nyth, adapting the tool to any codebase.
Price: Free
Key features
Another smart contract security tool developed by Trail of Bits is Slither. It is a Python-based static analysis tool that provides a wide range of vulnerability detectors for Solidity code.
Its fast execution time, low false-positive rate, and ability to integrate into continuous integration (CI) pipelines make it a valuable asset for developers who want to improve the security of their code.
With 93 detectors, Slither can detect a wide range of vulnerabilities, has a solid trust score, and can speed up auditors' efficiency. It is also compatible with various frameworks, such as Hardhat, decentralized app (dApp) tools, and, of course, Foundry.
Price: Free
Key features
Halmos, developed by a16z, is a pioneering open-source smart contract security tool that offers formal verification tailored explicitly for Ethereum smart contracts. Through its innovative use of symbolic testing, it uniquely bridges the gap between traditional unit testing and formal specifications.
Formal Verification requires advanced mathematical and arithmetic skills, and a writing test with Halmos requires a special setup and reading of the documentation. This rigorous approach ensures high precision in evaluating smart contracts, aiming to iron out potential flaws and guarantee flawless operation.
Price: Free
Key features
Foundry gets a special mention here. It’s a tool that should never be missed in the smart contract developer stack.
It is designed for smart contract development and auditing. It simplifies tasks, from managing project dependencies to compiling, testing, and deploying smart contracts, as well as direct blockchain interactions and testing.
Foundry offers features like automatic compiler version detection and efficient caching, and it stands out with its fuzz testing capabilities.
Price: Free
Key features
It is not an auditing tool per se, but it is the best place for auditors to learn about vulnerabilities and security breaches.
Solodit, another tool in the Cyfrin ecosystem, aggregates over 15,000 security vulnerabilities and bug bounties from various security firms and top researchers worldwide.
The platform aims to strengthen the security of dApps and smart contracts by providing detailed reports on vulnerabilities, including:
Solodit also offers advanced search and filtering tools to help users easily find specific vulnerabilities and bounties.
Price: Free
Key features
We only examined eight (or nine if we count Recon) blockchain security and auditing tools, but the real behemoth is too large to be covered in a single article.
Github user @shanzson gathered an exciting resource with helpful information, links, and tools that any auditor should consider using. We highly recommend it.
In this list of the top smart contract auditing and security tools, we’ve seen eight different tools that you shouldn’t miss in your toolkit!
Each tool brings unique strengths, catering to different aspects of smart contract security. Remember, the tools are just that, tools.
The most important factor in a successful audit is the auditor, not the tool. Including tools and software in your audit stack will help you perform better, find more vulnerabilities, and improve your workflows.
If you want to learn how to become a blockchain developer or auditor and learn from the experts to write robust and reliable smart contracts, join Cyfrin Updraft now and start learning for free!
