Static Analyzer for Solidity

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Slither, the Solidity source analyzer


Build Status Slack Status PyPI version

Slither is a Solidity static analysis framework written in Python 3. 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
  • Identifies where the error condition occurs in the source code
  • Easily integrates into continuous integration and Truffle 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

Bugs and Optimizations Detection

Run Slither on a Truffle/Embark/Dapp/Etherlime application:

slither .

Run Slither on a single file:

$ slither tests/uninitialized.sol

For additional configuration, see the usage documentation.

Use solc-select if your contracts require older versions of solc.


Num Detector What it Detects Impact Confidence
1 rtlo Right-To-Left-Override control character is used High High
2 shadowing-state State variables shadowing High High
3 suicidal Functions allowing anyone to destruct the contract High High
4 uninitialized-state Uninitialized state variables High High
5 uninitialized-storage Uninitialized storage variables High High
6 arbitrary-send Functions that send ether to arbitrary destinations High Medium
7 controlled-delegatecall Controlled delegatecall destination High Medium
8 reentrancy-eth Reentrancy vulnerabilities (theft of ethers) High Medium
9 erc20-interface Incorrect ERC20 interfaces Medium High
10 erc721-interface Incorrect ERC721 interfaces Medium High
11 incorrect-equality Dangerous strict equalities Medium High
12 locked-ether Contracts that lock ether Medium High
13 shadowing-abstract State variables shadowing from abstract contracts Medium High
14 constant-function-asm Constant functions using assembly code Medium Medium
15 constant-function-state Constant functions changing the state Medium Medium
16 reentrancy-no-eth Reentrancy vulnerabilities (no theft of ethers) Medium Medium
17 tx-origin Dangerous usage of tx.origin Medium Medium
18 unchecked-lowlevel Unchecked low-level calls Medium Medium
19 unchecked-send Unchecked send Medium Medium
20 uninitialized-local Uninitialized local variables Medium Medium
21 unused-return Unused return values Medium Medium
22 shadowing-builtin Built-in symbol shadowing Low High
23 shadowing-local Local variables shadowing Low High
24 void-cst Constructor called not implemented Low High
25 calls-loop Multiple calls in a loop Low Medium
26 reentrancy-benign Benign reentrancy vulnerabilities Low Medium
27 reentrancy-events Reentrancy vulnerabilities leading to out-of-order Events Low Medium
28 timestamp Dangerous usage of block.timestamp Low Medium
29 assembly Assembly usage Informational High
30 deprecated-standards Deprecated Solidity Standards Informational High
31 erc20-indexed Un-indexed ERC20 event parameters Informational High
32 low-level-calls Low level calls Informational High
33 naming-convention Conformance to Solidity naming conventions Informational High
34 pragma If different pragma directives are used Informational High
35 solc-version Incorrect Solidity version Informational High
36 unused-state Unused state variables Informational High
37 reentrancy-unlimited-gas Reentrancy vulnerabilities through send and transfer Informational Medium
38 too-many-digits Conformance to numeric notation best practices Informational Medium
39 constable-states State variables that could be declared constant Optimization High
40 external-function Public function that could be declared as external Optimization High

See the Detectors Documentation for more information. By default, all the detectors are run.

Check out Crytic to get access to additional Slither's detectors and GitHub integration.


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.

How to install

Slither requires Python 3.6+ and solc, the Solidity compiler.

Using Pip

$ pip3 install slither-analyzer

Using Git

$ git clone && cd slither
$ python3 install

We recommend using an 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

Getting Help

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


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


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