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Slither is a Solidity & Vyper static analysis framework written in Python3. It runs a suite of vulnerability detectors, prints visual information about contract details, and provides an API to easily write custom analyses. Slither enables developers to find vulnerabilities, enhance their code comprehension, and quickly prototype custom analyses.


  • Detects vulnerable Solidity code with low false positives (see the list of trophies)
  • Identifies where the error condition occurs in the source code
  • Easily integrates into continuous integration and Hardhat/Foundry builds
  • Built-in 'printers' quickly report crucial contract information
  • Detector API to write custom analyses in Python
  • Ability to analyze contracts written with Solidity >= 0.4
  • Intermediate representation (SlithIR) enables simple, high-precision analyses
  • Correctly parses 99.9% of all public Solidity code
  • Average execution time of less than 1 second per contract
  • Integrates with Github's code scanning in CI
  • Support for Vyper smart contracts


Run Slither on a Hardhat/Foundry/Dapp/Brownie application:

slither .

This is the preferred option if your project has dependencies as Slither relies on the underlying compilation framework to compile source code.

However, you can run Slither on a single file that does not import dependencies:

slither tests/uninitialized.sol

How to install

Slither requires Python 3.8+. If you're not going to use one of the supported compilation frameworks, you need solc, the Solidity compiler; we recommend using solc-select to conveniently switch between solc versions.

Using Pip

python3 -m pip install slither-analyzer

Using Git

git clone && cd slither
python3 -m pip install .

We recommend using a Python virtual environment, as detailed in the Developer Installation Instructions, if you prefer to install Slither via git.

Using Docker

Use the eth-security-toolbox docker image. It includes all of our security tools and every major version of Solidity in a single image. /home/share will be mounted to /share in the container.

docker pull trailofbits/eth-security-toolbox

To share a directory in the container:

docker run -it -v /home/share:/share trailofbits/eth-security-toolbox


  • For GitHub action integration, use slither-action.
  • To generate a Markdown report, use slither [target] --checklist.
  • To generate a Markdown with GitHub source code highlighting, use slither [target] --checklist --markdown-root (replace ORG, REPO, COMMIT)


Num Detector What it Detects Impact Confidence
1 abiencoderv2-array Storage abiencoderv2 array High High
2 arbitrary-send-erc20 transferFrom uses arbitrary from High High
3 array-by-reference Modifying storage array by value High High
4 encode-packed-collision ABI encodePacked Collision High High
5 incorrect-shift The order of parameters in a shift instruction is incorrect. High High
6 multiple-constructors Multiple constructor schemes High High
7 name-reused Contract's name reused High High
8 protected-vars Detected unprotected variables High High
9 public-mappings-nested Public mappings with nested variables High High
10 rtlo Right-To-Left-Override control character is used High High
11 shadowing-state State variables shadowing High High
12 suicidal Functions allowing anyone to destruct the contract High High
13 uninitialized-state Uninitialized state variables High High
14 uninitialized-storage Uninitialized storage variables High High
15 unprotected-upgrade Unprotected upgradeable contract High High
16 codex Use Codex to find vulnerabilities. High Low
17 arbitrary-send-erc20-permit transferFrom uses arbitrary from with permit High Medium
18 arbitrary-send-eth Functions that send Ether to arbitrary destinations High Medium
19 controlled-array-length Tainted array length assignment High Medium
20 controlled-delegatecall Controlled delegatecall destination High Medium
21 delegatecall-loop Payable functions using delegatecall inside a loop High Medium
22 incorrect-exp Incorrect exponentiation High Medium
23 incorrect-return If a return is incorrectly used in assembly mode. High Medium
24 msg-value-loop msg.value inside a loop High Medium
25 reentrancy-eth Reentrancy vulnerabilities (theft of ethers) High Medium
26 return-leave If a return is used instead of a leave. High Medium
27 storage-array Signed storage integer array compiler bug High Medium
28 unchecked-transfer Unchecked tokens transfer High Medium
29 weak-prng Weak PRNG High Medium
30 domain-separator-collision Detects ERC20 tokens that have a function whose signature collides with EIP-2612's DOMAIN_SEPARATOR() Medium High
31 enum-conversion Detect dangerous enum conversion Medium High
32 erc20-interface Incorrect ERC20 interfaces Medium High
33 erc721-interface Incorrect ERC721 interfaces Medium High
34 incorrect-equality Dangerous strict equalities Medium High
35 locked-ether Contracts that lock ether Medium High
36 mapping-deletion Deletion on mapping containing a structure Medium High
37 shadowing-abstract State variables shadowing from abstract contracts Medium High
38 tautological-compare Comparing a variable to itself always returns true or false, depending on comparison Medium High
39 tautology Tautology or contradiction Medium High
40 write-after-write Unused write Medium High
41 boolean-cst Misuse of Boolean constant Medium Medium
42 constant-function-asm Constant functions using assembly code Medium Medium
43 constant-function-state Constant functions changing the state Medium Medium
44 divide-before-multiply Imprecise arithmetic operations order Medium Medium
45 out-of-order-retryable Out-of-order retryable transactions Medium Medium
46 reentrancy-no-eth Reentrancy vulnerabilities (no theft of ethers) Medium Medium
47 reused-constructor Reused base constructor Medium Medium
48 tx-origin Dangerous usage of tx.origin Medium Medium
49 unchecked-lowlevel Unchecked low-level calls Medium Medium
50 unchecked-send Unchecked send Medium Medium
51 uninitialized-local Uninitialized local variables Medium Medium
52 unused-return Unused return values Medium Medium
53 incorrect-modifier Modifiers that can return the default value Low High
54 shadowing-builtin Built-in symbol shadowing Low High
55 shadowing-local Local variables shadowing Low High
56 uninitialized-fptr-cst Uninitialized function pointer calls in constructors Low High
57 variable-scope Local variables used prior their declaration Low High
58 void-cst Constructor called not implemented Low High
59 calls-loop Multiple calls in a loop Low Medium
60 events-access Missing Events Access Control Low Medium
61 events-maths Missing Events Arithmetic Low Medium
62 incorrect-unary Dangerous unary expressions Low Medium
63 missing-zero-check Missing Zero Address Validation Low Medium
64 reentrancy-benign Benign reentrancy vulnerabilities Low Medium
65 reentrancy-events Reentrancy vulnerabilities leading to out-of-order Events Low Medium
66 return-bomb A low level callee may consume all callers gas unexpectedly. Low Medium
67 timestamp Dangerous usage of block.timestamp Low Medium
68 assembly Assembly usage Informational High
69 assert-state-change Assert state change Informational High
70 boolean-equal Comparison to boolean constant Informational High
71 cyclomatic-complexity Detects functions with high (> 11) cyclomatic complexity Informational High
72 deprecated-standards Deprecated Solidity Standards Informational High
73 erc20-indexed Un-indexed ERC20 event parameters Informational High
74 function-init-state Function initializing state variables Informational High
75 incorrect-using-for Detects using-for statement usage when no function from a given library matches a given type Informational High
76 low-level-calls Low level calls Informational High
77 missing-inheritance Missing inheritance Informational High
78 naming-convention Conformity to Solidity naming conventions Informational High
79 pragma If different pragma directives are used Informational High
80 redundant-statements Redundant statements Informational High
81 solc-version Incorrect Solidity version Informational High
82 unimplemented-functions Unimplemented functions Informational High
83 unused-state Unused state variables Informational High
84 costly-loop Costly operations in a loop Informational Medium
85 dead-code Functions that are not used Informational Medium
86 reentrancy-unlimited-gas Reentrancy vulnerabilities through send and transfer Informational Medium
87 similar-names Variable names are too similar Informational Medium
88 too-many-digits Conformance to numeric notation best practices Informational Medium
89 cache-array-length Detects for loops that use length member of some storage array in their loop condition and don't modify it. Optimization High
90 constable-states State variables that could be declared constant Optimization High
91 external-function Public function that could be declared external Optimization High
92 immutable-states State variables that could be declared immutable Optimization High
93 var-read-using-this Contract reads its own variable using this Optimization High

For more information, see


Quick Review Printers

In-Depth Review Printers

To run a printer, use --print and a comma-separated list of printers.

See the Printer documentation for the complete lists.


See the Tool documentation for additional tools.

Contact us to get help on building custom tools.

API Documentation

Documentation on Slither's internals is available here.

Getting Help

Feel free to stop by our Slack channel (#ethereum) for help using or extending Slither.


How do I exclude mocks or tests?

How do I fix "unknown file" or compilation issues?

  • Because slither requires the solc AST, it must have all dependencies available. If a contract has dependencies, slither contract.sol will fail. Instead, use slither . in the parent directory of contracts/ (you should see contracts/ when you run ls). If you have a node_modules/ folder, it must be in the same directory as contracts/. To verify that this issue is related to slither, run the compilation command for the framework you are using e.g npx hardhat compile. That must work successfully; otherwise, slither's compilation engine, crytic-compile, cannot generate the AST.


Slither is licensed and distributed under the AGPLv3 license. Contact us if you're looking for an exception to the terms.


Trail of Bits publication

External publications

Title Usage Authors Venue Code
ReJection: A AST-Based Reentrancy Vulnerability Detection Method AST-based analysis built on top of Slither Rui Ma, Zefeng Jian, Guangyuan Chen, Ke Ma, Yujia Chen CTCIS 19
MPro: Combining Static and Symbolic Analysis forScalable Testing of Smart Contract Leverage data dependency through Slither William Zhang, Sebastian Banescu, Leodardo Pasos, Steven Stewart, Vijay Ganesh ISSRE 2019 MPro
ETHPLOIT: From Fuzzing to Efficient Exploit Generation against Smart Contracts Leverage data dependency through Slither Qingzhao Zhang, Yizhuo Wang, Juanru Li, Siqi Ma SANER 20
Verification of Ethereum Smart Contracts: A Model Checking Approach Symbolic execution built on top of Slither’s CFG Tam Bang, Hoang H Nguyen, Dung Nguyen, Toan Trieu, Tho Quan IJMLC 20
Smart Contract Repair Rely on Slither’s vulnerabilities detectors Xiao Liang Yu, Omar Al-Bataineh, David Lo, Abhik Roychoudhury TOSEM 20 SCRepair
Demystifying Loops in Smart Contracts Leverage data dependency through Slither Ben Mariano, Yanju Chen, Yu Feng, Shuvendu Lahiri, Isil Dillig ASE 20
Trace-Based Dynamic Gas Estimation of Loops in Smart Contracts Use Slither’s CFG to detect loops Chunmiao Li, Shijie Nie, Yang Cao, Yijun Yu, Zhenjiang Hu IEEE Open J. Comput. Soc. 1 (2020)
SAILFISH: Vetting Smart Contract State-Inconsistency Bugs in Seconds Rely on SlithIR to build a storage dependency graph Priyanka Bose, Dipanjan Das, Yanju Chen, Yu Feng, Christopher Kruegel, and Giovanni Vigna S&P 22 Sailfish
SolType: Refinement Types for Arithmetic Overflow in Solidity Use Slither as frontend to build refinement type system Bryan Tan, Benjamin Mariano, Shuvendu K. Lahiri, Isil Dillig, Yu Feng POPL 22
Do Not Rug on Me: Leveraging Machine Learning Techniques for Automated Scam Detection Use Slither to extract tokens' features (mintable, pausable, ..) Mazorra, Bruno, Victor Adan, and Vanesa Daza Mathematics 10.6 (2022)
MANDO: Multi-Level Heterogeneous Graph Embeddings for Fine-Grained Detection of Smart Contract Vulnerabilities Use Slither to extract the CFG and call graph Hoang Nguyen, Nhat-Minh Nguyen, Chunyao Xie, Zahra Ahmadi, Daniel Kudendo, Thanh-Nam Doan and Lingxiao Jiang IEEE 9th International Conference on Data Science and Advanced Analytics (DSAA, 2022) ge-sc
Automated Auditing of Price Gouging TOD Vulnerabilities in Smart Contracts Use Slither to extract the CFG and data dependencies Sidi Mohamed Beillahi, Eric Keilty, Keerthi Nelaturu, Andreas Veneris, and Fan Long 2022 IEEE International Conference on Blockchain and Cryptocurrency (ICBC) Smart-Contract-Repair

If you are using Slither on an academic work, consider applying to the Crytic $10k Research Prize.