What ASP.NET Core can do
ASP.NET Core isn't a single technology but a set of tools for different kinds of web projects, combined in one framework:
- server-rendered pages for portals and dashboards where simplicity and good indexing matter;
- Web API for mobile apps, separate frontends and data exchange with other systems;
- Blazor, an interactive browser UI written in C# instead of JavaScript;
- real-time connections, so pages receive updates without reloading;
- background services inside the same application for email campaigns, data sync and file processing.
All of these share configuration, the user system and database access, so they're easy to combine in one project.
ASP.NET Core advantages
- High performance. In independent benchmarks the framework consistently ranks among the fastest server-side frameworks, which in practice means fewer servers for the same load.
- Built-in user system. Sign-up, login, email confirmation, two-factor authentication and roles come as ready-made mechanisms that just need configuring.
- Sign-in with corporate accounts. An employee portal can let staff sign in with the same account they use for Microsoft 365 email.
- Flexible deployment. Applications run on Linux and in containers, so you're not tied to Windows servers.
- One language for everything. With Blazor, even the UI can be written in C#, which makes life easier for a small team.
Limitations
- Few ready-made modules for typical websites. A catalog, cart or blog has to be either built or taken from a CMS. For a standard online store this costs more than on PHP platforms.
- Blazor is still less widespread than React or Angular. For public sites with large audiences and complex design, a separate frontend built on popular libraries is more practical.
- Frequent releases. A new platform version ships every year, some with short support windows. Upgrades need to be part of the work plan.
- Legacy projects don't migrate automatically. Web Forms from classic ASP.NET aren't supported in the new framework, so those pages have to be rewritten.
When to consider alternatives
If your company runs on the Java ecosystem and your developers and servers are already set up for it, Spring Boot handles the same tasks. If the main goal is a content site managed by marketers, Umbraco makes more sense: it's a content management system built on ASP.NET Core, so custom logic can be added when needed.
Server-rendered pages, Blazor or a separate frontend
This is the key architectural decision at the start, and it determines both the budget and future maintenance.
Server-rendered pages are the simplest and most affordable option for portals and dashboards with forms, tables and documents. They're indexed well by search engines and load fast.
Blazor suits internal tools with rich interaction: drag and drop, filters, inline table editing. The upside is one language and one team; the downside is fewer ready-made components than in the JavaScript world.
A separate frontend in React or Angular makes sense when the product is large, used by customers, and ASP.NET Core also serves a mobile app. Angular is often chosen for enterprise .NET projects because of its similarly strict approach to code structure.
Data and security
The database is most often PostgreSQL, or Microsoft products if the company already uses them. We manage the database schema through migrations, so every change is recorded and can be replayed on staging and production servers.
On security, ASP.NET Core has good defaults: request forgery protection, data encryption and enforced HTTPS. We add permission checks on every action, API rate limiting and an audit log of important operations. For portals that handle personal data, this isn't optional; it's a required part of the work.
Modernizing legacy ASP.NET projects
Many corporate portals run on classic ASP.NET, written for an older version of the platform that only runs on Windows. They do their job, but they're tied to Windows servers, slower, and don't work well with newer libraries.
Rewriting such a portal in one go is risky. We stand up a new ASP.NET Core application alongside the old one and migrate sections one at a time: users keep working while the old code is gradually phased out. We start with what changes most often or slows things down the most.
In parallel we update database access and the authentication system, since they're usually what keeps a legacy project on outdated libraries. Once the last section is migrated, the old application is simply switched off.
What affects cost
- How the UI is built: server-rendered pages, Blazor, or a separate frontend with an API.
- Users and access: number of roles, corporate sign-in, two-factor authentication requirements.
- Integrations: accounting systems, CRM, Microsoft products, payment providers.
- Load and availability requirements: number of concurrent users, redundancy.
- Condition of the existing project: for modernization, the framework version, number of Web Forms pages and test coverage.
We plan the work so that after each stage part of the portal is already live, and you can reprioritize the next one.
FAQ
Do I need a Microsoft license to use ASP.NET Core? No, the framework is free. You only pay for hosting and, possibly, other Microsoft products if you choose them.
Is ASP.NET Core suitable for a public website with SEO? Yes, pages can be rendered on the server and are indexed well. For a content site, Umbraco is more convenient.
Our portal runs on classic ASP.NET. How much of it can we keep? Business logic and the database can usually be preserved. A Web Forms interface will have to be rewritten. We'll give you a more precise answer after a code audit.
Blazor or React? For internal tools with a small team, Blazor is often the better value. For a large customer-facing product, React or Angular.
Why Promodex
We explain architectural decisions in plain language: why server-rendered pages instead of a separate frontend, why this particular sign-in scheme. Over 750+ projects since 2015, we've seen how costly decisions become when nobody explains them to the client. Your portal is built by our own in-house team, we adapt the engagement model to your processes, and after launch we keep the portal updated along with the platform.
