XML Plus is a powerful XML viewer that supports both CSS and XPath selectors. It is a Chrome add-on developed by eGust and is available for free.

With XML Plus, users can easily navigate and analyze XML files using text and regular expression search. The add-on offers both `querySelectorAll` and jQuery flavors of CSS selectors, making it flexible for different user preferences. Notably, the regular expression search is case-insensitive, allowing for more accurate and efficient searches.

One of the standout features of XML Plus is its optimization for large XML files, making it ideal for handling files larger than 1MB. Additionally, XML Plus is a stand-alone version, which means it bypasses Chrome's slow loading process, resulting in extremely fast performance.

XML Plus also provides a global `x` variable in DevTools, offering easy access to various XML-related objects and helpers. This includes the raw XML document object, root XML element object, current selected node, jQuery bound on the root element, search history, and helpers for jQuery, CSS, regular expression, text, and XPath searches.

Overall, XML Plus is a comprehensive XML viewer that offers powerful features and optimization for large files. Whether you're a developer or a user working with XML files, XML Plus provides a convenient and efficient solution.