XLSX Edit Pro is a complete spreadsheet program for XLS,XLSX,CSV files. Create, open, and edit your own spreadsheets or spreadsheets from Office / Excel.

XLSX Edit Pro is the best way to work with Excel docs without installing MS Office or having the Internet connection on your device. It’s a very useful tool for everyone who needs to create or edit Excel documents. The app includes all the necessary Excel functions and formulas, as well as various possibilities for document formatting.

In addition to the above.
It can also encrypt excel files.