Senior .NET Backend Engineer – Modernization & APIs

Vaco; Tempe (AZ); On-site; USD 135,000 - 165,000; Full time

Benefits offered by this job

Bonus opportunity

401(k) with employer match

Generous PTO

Job summary

Vaco, in collaboration with a national wealth management technology leader, seeks a Senior Software Engineer focused on backend .NET development, API design, and modernization of core platform applications. Based in Tempe, you will join a new engineering team as one of the most senior individual contributors locally.

The role emphasizes rewriting legacy systems into modern .NET, building scalable APIs, working with SQL Server, and interfacing with multiple data sources.

Qualifications

• 7+ years of professional software engineering experience delivering production systems.
• Strong backend development experience with C#, .NET, and modern .NET frameworks.
• Experience modernizing legacy applications or incremental improvements of older systems.
• Strong SQL database experience, including SQL Server or comparable relational databases.
• Experience designing and building RESTful APIs and integration layers.
• Experience with third-party API integrations and data ingestion from multiple sources.
• Experience writing unit and integration tests and working within CI/CD delivery practices.
• Experience working in Agile or Scrum environments with cross-functional teams.
• Strong communication skills with the ability to explain technical decisions clearly.
• Ability to operate as a senior individual contributor and mentor other engineers.

Responsibilities

• Design, build, test, and deploy backend services and APIs using C#, .NET, and modern engineering practices
• Support modernization efforts by helping rewrite legacy systems into modern .NET architecture
• Develop scalable API and integration patterns for data ingestion across multiple internal and third-party sources
• Work with SQL Server and related database technologies to build reliable, data-centric applications
• Translate product requirements and architecture guidance into maintainable, production-ready software
• Author technical design documentation and participate in design reviews for significant changes
• Build resilient integrations with clear contracts, versioning strategies, error handling, logging, and observability
• Write clean, testable code and contribute to unit, integration, and end-to-end testing practices
• Participate in code reviews focused on performance, maintainability, resiliency, and secure coding
• Troubleshoot production issues, support root-cause analysis, and improve application reliability
• Partner with product, architecture, QA, DevOps, and engineering peers in Agile delivery cycles
• Mentor junior and mid-level engineers while helping raise engineering standards across the team

Skills

C#

NET Framework / .NET Core

RESTful APIs

SQL Server

CI/CD

Agile / Scrum

Mentoring

Unit testing

Tools

Azure

Azure SQL

Azure Functions

Azure API Management

AWS

Job description

Vaco, in collaboration with a national wealth management technology leader, seeks a Senior Software Engineer focused on backend .NET development, API design, and modernization of core platform applications. Based in Tempe, you will join a new engineering team as one of the most senior individual contributors locally.

The role emphasizes rewriting legacy systems into modern .NET, building scalable APIs, working with SQL Server, and interfacing with multiple data sources.