S3Scanner is an open-source security tool that performs comprehensive scans of S3 buckets across S3-compatible APIs to identify misconfigurations and security vulnerabilities. The tool detects various security issues including publicly accessible buckets, unsecured storage containers, and buckets with improperly configured permissions that could lead to unauthorized access or data exposure. S3Scanner provides customizable scanning options and an accessible interface for security professionals and developers to assess their cloud storage security posture. The tool helps organizations identify and address S3 bucket misconfigurations before they can be exploited, supporting proactive cloud security management and compliance efforts.