XLSX Editor: XLS Spreadsheet - Your All-in-One XLSX Viewer and Editor. We develop XLSX Editor, the ultimate Android app designed for opening xlsx files viewer and xls file reader. With its powerful features, this app is the perfect companion for managing xlsx files. Let's explore the features of this xlsx file viewer anf xls reader app. 1. Offline File Viewing - xlsx & xls file viewer: 1. Quick and Convenient Navigation - xlsx reader:. 3. User-Friendly Interface: 4. Versatile Viewing Options: 5