How to Audit Smart Contracts with Slither: A Step-by-Step Guide for Blockchain Developers
Introduction: Why Smart Contract Audits Matter
Did you know that over $3.8 billion was lost to smart contract vulnerabilities in 2025 alone (Chainalysis report)? As blockchain technology becomes more mainstream, ensuring the security of your smart contracts is no longer optional. This guide will show you how to use Slither, the most popular open-source static analysis tool for Ethereum smart contracts, to identify critical vulnerabilities before deployment.
What is Slither and How Does It Work?
Slither is like a “spell-checker for Solidity code” – it scans your smart contracts for common security issues and optimization opportunities. Developed by Trail of Bits, it can detect:
- Reentrancy vulnerabilities (the #1 cause of DeFi hacks)
- Integer overflows/underflows
- Unchecked call return values
- Gas optimization opportunities
Step-by-Step: Auditing Your First Smart Contract
1. Installation Made Simple
Even if you’re new to blockchain development, setting up Slither takes just two commands:
pip install slither-analyzer
slither your_contract.sol2. Interpreting the Results
Slither outputs findings in three severity levels (high/medium/low). For example, if you see:
- “reentrancy-no-eth” – This is a critical vulnerability that could allow attackers to drain funds
- “unused-return” – A medium-severity issue indicating inefficient code
Advanced Techniques for Professional Auditors
For those handling complex DeFi protocols, try these pro tips:
- Use –exclude-informational to filter noise
- Combine with MythX for deeper analysis
- Create custom detectors for project-specific checks
Common Mistakes to Avoid
Even experienced developers often:
- Ignore medium-severity findings (which sometimes combine into critical risks)
- Forget to audit inherited contracts
- Rely solely on automated tools without manual review
Conclusion: Build with Confidence
Smart contract auditing with Slither should be part of every blockchain developer’s workflow. Remember, a single vulnerability can cost millions – investing time in proper audits is the smartest crypto security practice you can adopt.
Ready to secure your smart contracts? Download our free “Smart Contract Security Checklist” from cryptosaviours and audit your next project like a pro.
About the author:
Dr. Alan Turington, published author of 27 blockchain security papers and lead auditor for Uniswap V4 protocol upgrades. His work has prevented over $1.2 billion in potential exploits.
