# Introduction to Abblix OIDC Server

Abblix OIDC Server is a .NET library that implements OAuth 2.0 and [OpenID Connect](https://www.abblix.com/en/docs/glossary-overview#openid-connect) on the server side. It was built by developers who had spent years working with IdentityServer4 in production and accumulated a long list of things they would have designed differently. [We wrote up why that history led to a new library rather than another fork](https://www.abblix.com/en/docs/we-built-our-own-identity-server).

The result is a library built for ASP.NET Core from the ground up: not a port, not a wrapper, but an implementation that treats routing, middleware, model binding, and [dependency injection](https://www.abblix.com/en/docs/glossary-overview#di) as first-class primitives.

## What makes it different

### Certification across all profiles

Abblix OIDC Server is certified by the OpenID Foundation across all login and logout profiles (Basic, Implicit, Hybrid, Config, Dynamic, Form Post, 3rd Party-Init, and all logout variants) with zero failures and zero skipped tests in 600+ conformance checks. The results are public and independently verifiable at the OpenID Foundation site. This is the most objective measure of protocol correctness available, and it's the strongest argument we make.

### Designed for extensibility

Authentication flows need layering: consent steps, custom claims, overridden token lifetimes, tenant-specific logic. Abblix OIDC Server is structured around small, composable interfaces using Composite and Decorator patterns throughout. Each extension point is sized to the behavior you're changing, not a thousand-plus-line class you need to understand before touching.

### ASP.NET Core native

The library integrates with ASP.NET Core the way your own controllers do. Standard routing, standard filters, standard debugging: no parallel middleware world to learn. Teams already building on .NET don't hit a conceptual wall when they add Abblix OIDC Server.

### Built on [System.Text.Json.Nodes](https://learn.microsoft.com/en-us/dotnet/api/system.text.json.nodes) end to end

Claims are [JsonNode](https://learn.microsoft.com/en-us/dotnet/api/system.text.json.nodes.jsonnode) values, not name/string pairs. Complex JWT payloads (arrays, nested objects, typed values) work without serialization workarounds.

## What it covers

The library implements OAuth 2.0 and OpenID Connect flows, [PKCE](https://www.abblix.com/en/docs/glossary-overview#pkce), [token introspection](https://www.abblix.com/en/docs/glossary-overview#token-introspection) and revocation, [dynamic client registration](https://www.abblix.com/en/docs/glossary-overview#dynamic-client-registration), device authorization, [mutual TLS](https://www.abblix.com/en/docs/glossary-overview#mutual-tls-client-authentication), [pushed authorization requests](https://www.abblix.com/en/docs/glossary-overview#par), JWT-secured authorization requests, [CIBA](https://www.abblix.com/en/docs/glossary-overview#ciba), and the full OpenID Connect suite including session management, front-channel and [back-channel logout](https://www.abblix.com/en/docs/glossary-overview#back-channel-logout), and dynamic provider discovery. See [Implemented Standards](https://www.abblix.com/en/docs/implemented-standards) for the complete list with RFC references.

## What it doesn't do (yet)

Entity Framework Core and ASP.NET Identity stores are on the roadmap for Q4 2026. Until then, you implement the persistence interfaces yourself: typically 200-400 lines wired to whatever database you already use. If you actually need ready-made EF Core stores, that's the one thing to keep in mind.

## Where to go next

- **[Getting Started](https://www.abblix.com/en/docs/getting-started-guide)**: working OIDC provider in your ASP.NET Core app
- **[Abblix vs Duende IdentityServer vs OpenIddict](https://www.abblix.com/en/docs/comparison-duende-openiddict)**: how the three .NET options compare on protocol coverage, licensing, and architecture
- **[Authentication for SPAs with a BFF](https://www.abblix.com/en/docs/net-authentication-openid-connect-bff-spa)**: the Backend-for-Frontend pattern for browser apps, end to end
- **[Understanding the Architecture](https://www.abblix.com/en/docs/understanding-the-architecture)**: hexagonal design, endpoints, handlers, extension points
- **[Implemented Standards](https://www.abblix.com/en/docs/implemented-standards)**: full RFC reference list
- **[Product Roadmap](https://www.abblix.com/en/docs/product-roadmap)**: what's coming and when