Smart Contract Audit Experts
HYDN provide in-depth manual Smart Contract Audits for EVM compatible chains that go way beyond what you get with an AI Audit.
Get a fast quote on Telegram.Recent audits include: Metamask, Clearpool, Guru, Spire.
- $10B+
- Funds secured
- 100+
- Clients served
- 30+
- Chains monitored in real time
Trusted by industry leaders including:
What is a smart contract audit?
A smart contract audit is a detailed analysis of a project's smart contracts to find vulnerabilities and bugs before the code is deployed, while a fix still costs engineering time rather than user funds.
Once a contract is live, its code is immutable and its balance is public. A mistake that would be a quiet patch in a normal web application becomes permanent, visible, and directly profitable for someone else to exploit. An audit is the last point at which a flaw is still cheap to fix.
Automated scanners catch known patterns such as reentrancy signatures, missing access modifiers and unchecked return values. What they cannot do is reason about whether your protocol's economics still hold when someone is actively trying to break them. That takes understanding what your protocol is meant to do, which is why every HYDN audit is led by a human.
Blockchain security you can trust
HYDN is an industry leading Smart Contract Audit firm which has extensive experience working with a multitude of blockchain projects including Metamask, Consensys, Sablier, Revert Finance, Telos Foundation, Bittrex Global, Decubate, SushiSwap, Guru, Spire, StakeDAO and many, many more.
The rise of AI Audits has also coincided with the rise of web3 hacks. 2026 has seen a huge number of multimillion dollar exploits and this number continues to rise. The need for skilled human auditors is higher than ever and that is where HYDN's expertise lies.
Experienced Team
HYDN's team are CISSP, CCNP, GCIH, GREM, and GNFA certified and have worked uncovering some of the biggest cybersecurity hacks in history including the Olympic Destroyer hack in 2018.
CTF Champions
HYDN was the winners of the EthernautDAO CTF Hacking Challenge 2022 hacking the smart contracts twice in under 5 minutes. HYDN's Lead Auditor also placed as the highest solo competitor in the Paradigm CTF 2023.
How a HYDN audit works
Six stages, from first contact to final certification. At every point you know which stage you are in, what we need from you, and what you get at the end of it.
- 1
Contact
You send us your source code and tell us what the protocol is meant to do. Scope is agreed against a specific commit hash, so both sides know exactly what is being reviewed.
- 2
Quote
We read the code before we price it. Your quote reflects the actual risk in your contracts rather than a line count, and we tell you what is driving it.
- 3
Audit
Senior auditors review the code by hand, modelling how a motivated attacker would approach it. Tooling supports that work. It does not replace it.
- 4
Report
You receive a private report classifying every finding as critical, high, medium, low or informational, alongside redundant code and code maturity notes, each with clear remediation guidance.
- 5
Fixes
Your team remediates, and we stay available while you do. Up to two rounds of remediation review are included in every audit at no extra cost.
- 6
Certify
We re-examine your fixes to confirm they hold, then issue the final report and certification. You decide whether to publish it.
Typical turnaround
- Token or ERC-20
- 2 to 5 days
- Standard DeFi protocol
- 2 to 4 weeks
- Bridge or L1 system
- 1 to 3 months
The flaws that take funds
Every audit starts from the assumption that your contracts will be attacked by someone competent, patient and well funded. These are the classes of flaw we look for first, because these are the ones that empty protocols.
Reentrancy
A contract that calls out to another before updating its own state can be re-entered mid execution and drained. It is the oldest bug in Ethereum and it still lands, because the modern version hides inside a chain of cross contract calls rather than one obvious function.
What is a reentrancy attack?Oracle and price manipulation
If your protocol trusts a price, someone will try to move that price. Thin liquidity, spot price feeds and single source oracles all let an attacker create a profitable lie that only needs to be true for one block.
The dangers of oracle manipulationAccess control and admin surface
Missing modifiers, initialisers left callable, and privileged functions that were never meant to ship. Simple flaws with total consequences, and they are caught by reading the code rather than scanning it.
5 common smart contract vulnerabilitiesUpgradeability and proxy risk
Upgradeable contracts trade immutability for flexibility and inherit a whole new class of bug: storage collisions, uninitialised implementations, and an admin key that becomes the single largest risk in your system.
5 common smart contract vulnerabilitiesBusiness logic and economic flaws
Code that is correct line by line can still be wrong as a system. Rounding that favours the caller, incentives that quietly reward an attack, and invariants that hold in testing but not under adversarial pressure.
OWASP Smart Contract Top 10 for 2026Dangers of AI Audits and Code
Generated code compiles, reads well, and carries the confident tone of something that has already been checked. Frequently it has not been. We are finding a rising number of vulnerabilities that look completely idiomatic and are not.
The hidden dangers of AI generated codeProof you can read
Anyone can claim an attacker mindset. These are engagements where it was tested in public, against real money, on a clock.
SushiSwap RouteProcessor2
On the evening of 8 April 2023, HYDN monitoring caught an approval bug in SushiSwap's RouteProcessor2 contract. Weak input validation in processRoute() allowed an attacker to impersonate a V3Pool address and move tokens out of any account that had granted approval. We opened a joint war room with the Sushi team that same night and deployed a cross chain watcher contract to front run the attackers across eight chains, rescuing over $600,000 of user funds before they could be taken.
Read the full SushiSwap write upPosition Exchange Finding
A vulnerability report from a deployed contract our team found an issue in, published in full rather than summarised. You can read exactly what we found and how we wrote it up.
Read the reportCTF champions
HYDN won the EthernautDAO CTF hacking challenge in 2022, breaking the target contracts twice in under five minutes. Our lead auditor placed as the highest solo competitor in the Paradigm CTF 2023.
Read the EthernautDAO reportWhat drives the cost
We do not price audits by the line, because line count is a poor proxy for risk. These are the things that move your number.
- Logic density, not line count
- A 300 line bridge can carry more risk than a 3,000 line token. What matters is how much novel, high value logic sits behind each function, not how far you have to scroll.
- External integrations and oracles
- Every external call is a trust assumption. Protocols that lean on oracles, bridges or other people's contracts inherit their failure modes along with their features, and all of it has to be reviewed.
- Upgradeability and admin surface
- Proxies, timelocks and privileged roles expand what has to be reasoned about. An admin key is a convenience to you and a target to everyone else, so it gets the same scrutiny as the core logic.
- Existing test coverage
- Well tested, documented code audits faster and therefore costs less. Time we do not spend working out what your protocol is meant to do is time we spend trying to break it.
- Turnaround urgency
- Compressing a six week review into two means more senior people on it at once, and that carries a premium. We will tell you when a deadline is buying you a worse audit rather than a faster one.
Frequently asked questions
What is a smart contract audit?
A smart contract audit is a detailed analysis of a project's smart contracts to find vulnerabilities and bugs before the code is deployed. Because a deployed contract is immutable and holds funds, an audit is the last practical point at which a flaw can be fixed cheaply rather than exploited expensively.
How much does a smart contract audit cost?
We do not publish fixed prices, because a line count tells you almost nothing about risk. Cost is driven by logic density, external integrations, upgradeability, your existing test coverage and how fast you need it. Every quote is scoped against your actual contracts, and we tell you what is driving the number.
How long does a smart contract audit take?
Most token and ERC-20 audits take 2 to 5 days. A standard DeFi protocol takes 2 to 4 weeks. Bridges, L1s and ZK systems take 1 to 3 months. Compressed timelines are possible, but they cost more, and we will tell you if a deadline is buying you a worse audit.
Which chains and languages do you audit?
We audit Solidity smart contracts across all EVM compatible chains. Our real time monitoring covers more than 30 chains, which is a separate service from auditing. If you are building outside the EVM, talk to us first rather than assuming we cannot help.
What do I need to provide before an audit starts?
Documentation covering what the system is meant to do and why, any risks you are already worried about, linted code with warnings resolved, and a code freeze with a specific commit hash. Anything changed after the audit begins falls outside the agreed scope.
How are findings classified?
Findings are classified as critical, major or minor, alongside notes on redundant code, coding errors and code maturity. Every finding comes with remediation guidance as well as a severity label, so your team knows what to do about it.
Do you use AI or automated tools?
We use tooling, but no HYDN audit is led by it. Scanners are good at known patterns and poor at protocol specific logic, which is exactly where the expensive bugs live. A human decides what matters and why, and a human writes your report.
Is my audit report public or private?
Your initial report is private. Once findings are remediated, you decide whether to publish the final report and certification. Some clients publish everything, some publish nothing, and both are entirely reasonable.
Do you re-check our fixes?
Yes. Up to two rounds of remediation review are included in every audit. We re-examine your fixes to confirm they hold and have not introduced anything new, then issue the final report and certification.
What happens if you find a critical vulnerability?
We tell you immediately rather than saving it for the report. Critical findings are raised as soon as they are confirmed, so your team can begin work on a fix while the rest of the review continues.
HYDN vs Other Smart Contract Auditors
Why you should choose HYDN if you're serious about security...
Most audit companies don't take the time to get a proper understanding of what you are trying to achieve, they operate on high volumes with rapid, often automated, delivery.
Here at HYDN we first gather a deep understanding of what your project is trying to achieve and then we can ideate potential attack vectors and test them properly.
By operating this way, HYDN is able to properly test your code for vulnerabilities.
HYDN
- Detailed manual audits that uncover more vulnerabilities
- Deep understanding of your project to run proper vulnerability checks
- Hands on personal service
Other Auditors
- Rely heavily on automated tools or AI audits
- No consideration of project goals so only test for general attack vectors
- Poor quality service
Smart contract audit guides
What we review for each type of protocol and chain, what an audit costs, and how to prepare.
Don't wait until it's too late...
- Experienced Team
- Comprehensive Reports
- Affordable Pricing