Need to quickly generate an Excel file on the server (.NET) with no headache or need to import  another Excel file in your JS client?

I can recommend two libraries for their simplicity and ease of use.


To smooth transitioning from Excel files to electronic handling of data we offered our users possibility of importing data. As our application is web based it meant some JS library to work with Excel files. A bit of complication was that our users over time developed a habit of having all kinds of modifications in their “custom” Excel files. So something that would allow us easily work with different formats was a preference.

XLSX.JS library available on GitHub proved to be a good choice. I could only imagine how much better it is over some monsters that would only work in IE. I think starting documentation is fairly good, so I will just go through some bits and pieces from our use case.

Setting up XLSX.JS and reading files is straight forward: npm or bower, include of file and you are ready to write XLSX.readFile('test.xlsx') or, {type: 'binary'}).

Reading as binary is probably a better bet as it will work in IE, though you will have to write some code to implement FileReader.prototype.readAsBinaryString() in IE. You can have a look at our implementation of file-select component on gist.

Using XLSX in your JavaScript is fairly easy, though there might be some hiccups with parsing dates. See this gist.


We also have two use cases where we need to generate Excel file on the server. One was to generate some documentation for business rules so we can have it up to date and share with our users at all times. It was implemented as part of CI that would save a file to a file system. The other use case was downloading of business related data via web interface. These two were super easy to do with open source library called EPPlus.

You just add EPPlus through NuGet and start using (var excelPackage = new ExcelPackage(newFileInfo)). See the gist below. First file demonstrates how to operate with cells and the other one just shows how you can use streams to make file downloadable.

These two libraries really helped me to efficiently implement some of the Excel file business use cases.

Next time I will have to generate Excel file on server or read it on client I will most certainly use these two again.

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