Sustainsys

Identity and access, done right!

Sustainsys deliver expert consulting and development for Single Sign-On and API access control in ASP.NET.

We build and maintain Sustainsys.Saml2 (30M+ downloads), and as a certified Duende Software partner we deliver training, consulting and implementation for Duende IdentityServer.

Sustainsys.Saml2

One of the most widely used open-source SAML 2.0 libraries for ASP.NET Core, with 30M+ downloads. It is trusted across healthcare, banking and enterprise systems.

Free and open source, available on GitHub
Documentation on our docs site
Commercial support and consulting for teams that want expert backup when it matters

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Consulting

We specialize in Identity and Access Management for ASP.NET Core, with deep expertise in SAML 2.0, OpenID Connect, OAuth 2.x, Microsoft Entra ID and Duende IdentityServer.

We work with your team, not just alongside it
Knowledge transfer built in, so your developers understand the solution and can own it long term
Email support included in all consulting packages, with no hourly billing for quick follow-up questions

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Training

As a certified Duende Software training partner, we deliver their official workshops for ASP.NET developers:

Identity & Access Management for Modern Applications (3 days) – a thorough foundation for building with OpenID Connect on ASP.NET Core
OAuth 2.0 & OpenID Connect – the Good Parts (1 day) – a focused overview for teams that need to get up to speed fast

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Duende Software Partner

As an authorized Duende Software partner and reseller, we help you:

Choose the right tier – no more or less than you need
Procure your license – same price as buying directly from Duende
Get the most out of it – with consulting, implementation and training from certified experts

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Microsoft Entra ID

Many organizations run on Microsoft Entra ID. We help you connect it securely to your applications and choose the right setup for your users.

Integrate your ASP.NET applications with Entra ID for single sign-on and API access
Entra ID or IdentityServer? We help you choose, or combine both, based on your actual needs
External users and customers with Microsoft Entra External ID

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News

2026-10-19

Anders to speak at Swetugg Stockholm, February 2027

OAuth 2.0 and OpenID Connect sit behind almost every login and API call you make. But the standards aren’t standing still, and AI agents are now knocking on the door. At Swetugg Stockholm 2027, Anders Abel presents The future of OAuth, AAuth & OIDC, a session on where identity standards are heading and what it means for the solutions you’re building today.

2026-08-25

Anders is speaking at Swenug Stockholm this September!

He'll give an overview of Authentication and Authorization in ASP.NET Core — covering authentication schemes, ASP.NET Identity, data protection, and authorization policies, based on lessons from hundreds of customer projects.

2026-07-15

Anders Abel renewed as Microsoft MVP

Our founder - Anders Abel - has once again been recognized as a Microsoft Most Valuable Professional (MVP) in Security and Identity.

2026-06-09

Anders Abel - speaking at Øredev 2026

This November 4, Anders takes the stage at Øredev, in Malmö – one of Scandinavia's largest developer conferences. His talk – Application Code vs Library Code – is about one of the most common pitfalls in software development: applying library patterns where they don't belong.

2026-05-25

Suzanne Rudels joins as Chief Operating Officer

We're excited to welcome Suzanne Rudels to Sustainsys as our new COO. Suzanne will be working closely with our CEO, Anders Abel, to take shared responsibility for the company as a whole. That means strategy, planning, customer relations – both building new ones and taking good care of the ones we already have – as well as the day-to-day operations that keep everything running.

2026-05-20

NDC Oslo 2026

NDC Oslo is one of Europe's premier conferences for software developers, bringing together thousands of developers, architects, and technology leaders each year. We are excited that Anders is once again speaking at the conference this year.

2026-04-15

DevSum 2026 — Be part of the developer community

On June 1-3 2026, Stockholm becomes the meeting place for developers, architects and tech leaders from across the Nordics. Join us for two days of inspiration, hands-on learning and community — where every developer belongs. Anders will of course be there to guide you through OAuth and OpenID Connect.

2026-03-20

NDC Security

In March 2026, Anders Abel spoke at NDC Security in Oslo – one of the most respected security conferences for software developers. A four-day event brought together over 60 speakers across 66 sessions, all focused on the latest in software security.