ember-cli-dependency-checker is an Ember CLI addon that helps maintain healthy dependencies in your Ember.js projects. It analyzes your project's package.json and compares it against your actual code usage, identifying unused, missing, or incorrectly specified dependencies. This addon helps prevent errors, reduces your application's bundle size, and ensures a more stable development environment by enforcing accurate dependency declarations. Using ember-cli-dependency-checker can reduce conflicts when upgrading dependencies and improve overall project maintainability.