Hallmark provides a simple and efficient way to identify and flag potentially problematic JavaScript code patterns or "hallmarks." It analyzes abstract syntax trees (ASTs) generated from JavaScript code to detect specific constructs often associated with antipatterns, security vulnerabilities, or code style inconsistencies. This allows developers to proactively identify and address such issues during development, improving code quality and maintainability. It's customizable, allowing you to define your own hallmark rules.