ONIX Viewer is a free Chrome extension designed to enhance the readability of ONIX XML files, which are commonly used in the publishing industry. By transforming raw ONIX data into a more user-friendly format, this tool provides syntax highlighting and a collapsible tree structure that simplifies navigation through extensive datasets. Users can easily search, expand, or collapse sections, making it ideal for managing large product feeds.

The extension also features auto-collapsed product blocks that display essential information such as ISBN, form, and title, keeping lengthy lists manageable. It supports ONIX versions 3.0, 3.1, and older 2.1 documents, while also resolving EDItEUR code-lists inline for quick reference. Additionally, ONIX Viewer works with both local XML files and remote URLs, offering flexibility for users needing to access ONIX data in various formats.