Demand the
.NET Experts that Develop for Pepsi, AIG, and the F100.
Founded in 2002, we’re headquartered in NYC and supported by a global team committed to building software of lasting value.
A Leader in .NET Development
Since 2002, DOOR3 has specialized in delivering high-performance, scalable, and secure .NET solutions that drive business success. Our team has a deep understanding of .NET, a powerful open-source framework, enabling us to build and maintain complex applications with precision and efficiency.
We’ve been doing this a long time, since .NET was introduced. Our clients, including SaaS-based climate tech leader ResCentric, benefit from our peerless capacity to de-risk projects and tailor our solutions to align with your business goals to foster long-term success. We proudly serve the financial services, insurance, legal, healthcare, non-profit & education, construction & contracting, and retail industries.
Why DOOR3 for .NET ?
Expertise and Versatility
Since .NET’s release, DOOR3 has excelled at building diverse applications—from web and mobile to cloud—tailored to the specific needs of our clients.
Strong Security
.NET’s robust security features, including encryption and authentication, allows our dedicated DevOps team to protect your applications against known and novel threats.
Scalable Solutions
DOOR3 builds award-winning, scalable .NET applications that grow with your business, ensuring high performance as your needs evolve.
Efficient Development
DOOR3 developers have mastered Visual Studio tools, ensuring your projects are not only fast to market but also easy to maintain and update over time.
Why DOOR3?
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Developing since dial-up
We’ve been developing software longer than most of our competitors have existed. Founded in 2002, before your phone was smart, DOOR3 is supported by a global team of talented professionals building software of lasting value.
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On-time and on-budget
Delivering excellence — reliably. Large companies and small non-profits turn to DOOR3 for the same reason: value.
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Enjoy the journey
We bring empathy, collaboration, and shared purpose to all of our projects.
“They know design, they know technology, and most importantly, they stick around until they get it done. I would recommend DOOR3 to anyone who needs reliable Web design and mission-critical, robust software development.”
Patrick McGill, Director, Online Production CSTV/CBS Online, Inc
+30
reviews on Clutch
“The process was fun, and it was energizing to work with DOOR3.”
Alexis Lellios UX Manager, SaaS Company“They had a great team, and we have nothing but praise for them.”
Debbie Penko Chief Product Officer, RISA Tech“DOOR3 was able to put everything together and help us achieve what we wanted.”
Andrés Santos Senior Software Engineer, Retrievr IncA Leader In .NET