Essential XlsIO is a .NET library that can read and write Microsoft Excel files (BIFF 8 format). It features a full-fledged object model just like the Microsoft Office COM libraries. XlsIO does not use COM interop and is built from scratch in C#. It can be used on systems that do not have Microsoft Excel installed, making it an excellent report engine for tabular data.

Essential XlsIO can create new spreadsheets purely from code or templates, it has full support for formatting, styles for the cells, formulae, page setups etc. It has also many advanced features like Data validation, Charts, Conditional formatting, Comments, Rich text support and worksheet security.