AEM Chrome extension - This browser extension can be leveraged in non-production environments to debug why the UI is slow or broken. The extension allows you to view the sling request processing (filters executed, which servlet, error handlers, components, sling resources, etc). and any JCR queries that are executed during the page load.
Touch UI XRay Mode for debugging - This is a tool for debugging Touch UI element issues in non-production environments, it assists in identifying which resources belong to various UI elements.