Build Passkey Login with WebAuthn in C# ASP.NET Core

 Build Passkey Login with WebAuthn in C# ASP.NET Core

Passwords have quietly become the weakest link in almost every app we use. They get reused, guessed, leaked in breaches, and phished from people who should know better. So the real question isn't how do we make passwords stronger — it's how do we get rid of them altogether.

That's exactly what passkey login with WebAuthn does. And in this post (plus the full video walkthrough below), I show what it looks like to bring passwordless authentication into a modern C# ASP.NET Core application.

The trouble with passwords

Every password is a liability. Users pick weak ones, reuse them across sites, and forget them constantly — which means more support tickets, more abandoned sign-ups, and a bigger attack surface for you to defend. Even "strong" passwords fall apart the moment they're phished or caught in someone else's data breach.

For anyone building software, that's a problem you inherit whether you want it or not. The good news is the industry has finally agreed on a better way.

What is a passkey?

A passkey is a modern, passwordless way to sign in. Instead of typing a secret, users confirm who they are with something they already have and use every day — their face, their fingerprint, or their device PIN.

Behind the scenes it's powered by WebAuthn, an open standard backed by Apple, Google, and Microsoft. The beauty of it is simple: there's nothing for the user to remember, and nothing sensitive sitting on your servers waiting to be stolen. No password means no password to leak.

For the person logging in, it feels almost effortless. For the business running the app, it removes an entire category of security headaches.

Watch the full build

In the video below, I walk through what passkey login looks like in action inside an ASP.NET Core app — from signing in with biometrics to managing passkeys like a polished, production-ready feature.

Why passwordless login matters for your app

Switching to passkeys isn't just a security upgrade — it changes the whole experience:

• Stronger security by design. With no password to phish, reuse, or breach, the most common ways accounts get compromised simply stop working.
• A smoother sign-in. Logging in with a face or fingerprint is faster and friendlier than typing yet another password, which means fewer drop-offs at the door.
• Future-proofing. The biggest names in tech are already pushing users toward passkeys. Apps that adopt them now feel modern; the ones that don't will start to feel dated.

Built for modern .NET applications

What I find exciting is how naturally this fits into the ASP.NET Core world. Passwordless authentication used to feel like something reserved for huge platforms with dedicated security teams. It isn't anymore — it can live comfortably inside the kind of C# applications developers and businesses build every day, working smoothly across phones, laptops, and browsers.

The result is an app that feels premium the moment a user signs in, without asking them to do anything more than be themselves.

Ready to go passwordless?

Build Passkey Login with WebAuthn in C# ASP.NET Core

Passkeys are where authentication is heading, and getting there sooner is a real advantage — for security, for user experience, and for how modern your product feels.

If you're thinking about bringing passwordless login into your own ASP.NET Core app and want it done right, I'd love to help. Watch the full walkthrough above, subscribe for more, and reach out if you'd like to build this into your project.