Every change to a blog post on this website took a whopping 20 second delay before I could see the result.

The solution was really simple, really. And was committed in the README as a TODO over 3 years ago.

Companion to the ClosedXML series, specifically to Part 2: Formulas.
Covering the ClosedXML syntax and implemented functions.

See the ClosedXML example code for of all the functions as UnitTests.

Miscellaneous features

ClosedXML can do a whole lot more for you. This post covers some interesting stuff that didn’t really fit anywhere else.

In case your users want to continue working with the Excels after generation.

Not a problem for ClosedXML. Instead of calculating values and writing them to an excel, leverage the power of Excel formulas.

Quick tutorial about creating xlsx Excels with C# and the ClosedXML nuget package.

The blog posts only covers the most important functionality. More extensive code examples can be found in the GitHub project.

Last month, I had the opportunity to attend DDD Europe 2025 in the Queen Elisabeth Hall in Antwerp — a few inspiring days full of insights, ideas, and engaging discussions around Domain-Driven Design, software quality, and architecture. Here are some of my key takeaways:

You’ve developed the most fancy application and are running it on your Synology in a Docker container.

But you really don’t want that ugly “Not secure” when opening it. This series goes over your options, starting with the easiest one to setup: using the Synology nginx.

dotnet/machinelearning : ML.NET is an open source and cross-platform machine learning framework for .NET.

microsoft/LightGBM : A fast, distributed, high performance gradient boosting (GBT, GBDT, GBRT, GBM or MART) framework based on decision tree algorithms, used for ranking, classification and many other machine learning tasks.

After writing some code to fetch and mold the data, I was ready to train “my” AI, dubbed “PongRank” which was easy enough and all was good until I added a small WebApi to automate future syncing, retraining and predictions.