EPPlus VS QuestPDF

Like others, I recommend using the ImportExcel module. It uses and wraps EPPlus Software (EPPlus - Create advanced Excel spreadsheets using .NET (GitHub Project Old / New)) which is a DLL that is included with the ImportExcel PowerShell Module.

There is some additional samples at their old (abandoned) branch: https://github.com/JanKallman/EPPlus/tree/master/SampleApp

Love this version: https://www.nuget.org/packages/EPPlus/4.5.3.3

EPPlus ExcelDataReader NPOI

For reading JSON -> e.g. ServiceStack.Text. For writing into Excel -> Use EPPlus library version 4.5.3.3. This is the last version of EPPlus under the LGPL License (aka free for commercial uses). You can install it using Nuget Package manager: Which library were you using for CSharp?

If you mean library, the older version of EPPlus is still available.

My suggestion would be to avoid using Office Interop. When you use it, it creates a dependency on Office, meaning it has to be installed on the machine in order for your app to run. That's completely unnecessary and wasteful from licensing perspective. There are several packages on Nuget that allow you to work with Excel sheets without the need for Office to be loaded. A couple would be ClosedXML and EPPlus.

QuestPDF looks really good (I haven't used it) but I believe they changed their license recently.

I used that same library it worked great the only issue I had was the users would often have to manually set the scaling to fit to a page. I'm sure I could've fixed this in other ways if I was more competent with CSS but ended up just switching to use https://github.com/QuestPDF/QuestPDF in a backend instead of doing everything in front end.

Give this a try: QuestPDF

I think you should ask these questions in related discussion on Github: https://github.com/QuestPDF/QuestPDF/discussions/491

May I introduce you to QuestPDF!

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Like many have suggested, I also cast my vote on QuestPDF. No more +50MB library including a Chrome browser to render HTML so a PDF of it can be created, which took 2-3 seconds each time. But with QuestPDF, it's so much faster!

Also, the library is open-source, so you can take a look at the exact implementation of the layout engine. It is inspired by Flutter and WPF, though optimized for pageable content: https://github.com/QuestPDF/QuestPDF/tree/main/Source/QuestPDF/Elements