Senior API Backend Engineer (.NET/C#)

Emerald Resource Group; Kentucky; Hybrid; USD 90,000 - 125,000; Full time

Job summary

Emerald Resource Group is partnering with an innovative technology company building secure enterprise APIs powered by AI-enabled applications. This Senior API Backend Engineer (.NET/C#) role focuses on secure, scalable backend services and enterprise API layers.

Ideal candidates reside in Northeast Ohio or the Columbus area, enjoy a hybrid schedule with 2 days onsite weekly, and are available for an initial 12-month contract with strong extension potential.

Qualifications

• OAuth authentication and authorization expertise.
• Experience building enterprise-grade API backends.
• Strong focus on security, reliability and data integrity.

Responsibilities

• Design and develop enterprise API layers using SQL and .NET/C#.
• Build secure, scalable backend services supporting high-volume transactions.
• Work with Azure API Management to build and secure APIs.
• Design authentication and authorization using OAuth and modern identity standards.
• Develop and optimize SQL Server database interactions.
• Collaborate with senior engineers on modern API design and backend architecture.

Skills

OAuth authentication

C# / .NET

Azure API Management

SQL Server

API design

Security architecture

Job description

• U.S. Citizenship is required due to industry requirements.
• No C2C, third-party candidates, or visa sponsorship will be considered.
• Candidates must currently reside in Northeast Ohio or the Columbus, Ohio area.
• Hybrid schedule with 2 days per week onsite.
• Initial 12-month contract with a strong possibility of extension.

We're partnering with an innovative technology company that's building the next generation of secure enterprise APIs used by AI-powered applications. This isn't a traditional .NET development role, and it isn't an AI prompt engineering position.

We're looking for a senior backend engineer who has designed and built enterprise-grade API layers where security, authentication, authorization, and data integrity are mission critical. You'll help develop APIs that safely power business-critical transactions at scale.

What You’ll Be Working On as a Senior API Backend Engineer (.NET/C#)

• Design and develop enterprise API layers using SQL .NET/C#
• Build secure, scalable backend services supporting high-volume transactions
• Work with Azure API Management to build and secure APIs
• Design authentication and authorization using OAuth and modern identity standards
• Develop and optimize SQL Server database interactions
• Collaborate with senior engineers on modern API design and backend architecture

Required Experience for Senior API Backend Engineer (.NET/C#)

• OAuth authentication and authorization

If you've built secure backend platforms where reliability, authentication, and API design matter more than flashy front-end work, I'd love to talk with you.