Tag: Web

Deserialize JSON into derived or abstract types: $type discriminators, [JsonPolymorphic] in .NET 7+, and a custom JsonConverter for legacy payloads.

I wanted a Mastodon address on my own domain without running a server. The trick is WebFinger: serve your Mastodon instance’s WebFinger JSON at /.well-known/webfinger on your domain, and @you@yourdomain resolves to your existing account. I use it as a forwarding address that survives switching servers. Updated October 2026: Mastodon and the instances running it have changed since 2022, so the UI may not match what you see in the screenshots or my descriptions. The WebFinger part works the same way.

A practical guide to the ASP.NET Core rate limiting middleware: fixed window, sliding window, token bucket and concurrency limiters, per-IP limits, and returning a 429.

Your web application is running fine, and your users are behaving as expected. Life is good! Is it, though…? Users are probably using your application in ways you did not expect. Crazy usage patterns resulting in more requests than expected, request bursts when users come back to the office after the weekend, and more!

In this post, let’s see how we can create an ASP.NET Core Tag Helper to show or hide UI elements based on authorization policies. But before we do so, let’s start with a quick introduction outlining why you may want to do this. The web front-end of SpeakerTravel, a side project that helps simplify travel booking for speakers at conferences and events, is built using ASP.NET MVC and Razor Pages. As it goes with many applications, there is going to be some point where you need authentication, and equally important, authorization.

This week, I was presenting at IglooConf (Indexing and searching NuGet org with Azure Functions and Search). During one of the demos, I casually used a feature we shipped with the latest Azure Toolkit for JetBrains Rider: when the Azure Functions host is running on a development machine, Rider lets us trigger functions from the gutter by generating an HTTP request for it.

Right now, I’m having fun building a .NET Core client library for JetBrains Space. Part of that client library will be ASP.NET Core authentication, to help in making authentication with your Space organization easy. Think of something like this: This should look very familiar if you are building an ASP.NET Core application that uses something like Microsoft Account, Google, Azure Active Directory/B2C, or anything that uses the Microsoft.AspNetCore.Authentication.OAuth namespace. There are many of those extensions that help register an authentication handler for a specific service.

Many developers are building Single-Page Applications (SPAs) using popular frameworks like Angular, React or VueJS. They all come with an easy way to generate all required HTML, CSS, JavaScript and Webpack artifacts required to deploy to production, usually an NPM script like npm run build away. Having to build all those artifacts multiple times while developing on our local machine is not too pleasant, all of them come with a way to launch a development server that hot reloads artifacts when needed, usually another NPM script (such as npm run start) away.

Recently, someone asked me to look at their ASP.NET MVC application and help figure out why a certain request was taking 16 seconds to complete. It’s always fun to look at those things, so I could not pass on this nerd snipe. Much like with hunting serial killers, you have to become one with the scene at hand. Watch the crime scene. Look at the things that happen, and observe. How can you observe a web application? The browser is a good start. Since this specific call was returning JSON data, I thought it easier to look at it in Fiddler instead. A typical response looked like this:

At Microsoft Build 2018, a number of Azure App Service on Linux enhancements were announced. One that I was interested in was this one: Remote debugging, in public preview: You can now choose to remote debug your Node.JS applications running on App Service on Linux. Sweet! But… how? The blog post did not mention a lot of details on the debugging part, so let’s walk through it, shall we? Remote debugging of Node.js apps on Azure App Service from WebStorm! First of all, we will need a number of things on our machine: The latest version of the Azure CLI 2.0