Create your own custom rules to highlight issues specific to your codebase as rule violations when you scan your code. Why? When your codebase has specific and repetitive coding issues that you want to address, you can use the built-in rules of Salesforce Code Analyzer to find these rule violations. But sometimes the problems exist only in the context of your codebase—and sometimes Code Analyzer’s built-in rules won’t catch them—so you need your own custom rules.

You can author your own custom PMD or ESLint rules. Because PMD and ESLint custom rules work differently, Code Analyzer deals with each in distinct ways.