Staff Software Engineer (C#/.NET) – API & Microservices

StoneX Group Inc.; Winter Park (FL); On-site; USD 120,000 - 160,000; Full time

Job summary

StoneX Group Inc. is seeking a Staff Software Engineer to join the API & Middleware Group in Winter Park, FL. You will design and operate high‑performance services, contribute to architecture, and drive reliability while collaborating with engineers, tech leads, and QA partners.

You will work with C#, .NET Core, Kafka, and cloud technologies, focusing on scalable middleware and core platform services used globally. The role offers an in‑office environment four days a week in Florida.

Qualifications

• 3+ years of professional experience building distributed systems using C# / .NET
• Strong experience with .NET Core / ASP.NET Core
• Experience with event‑driven architectures and Kafka or similar messaging platforms
• Solid understanding of distributed systems, concurrency, and performance tuning
• Strong SQL experience with relational databases; NoSQL exposure is a plus
• Experience in containerized, cloud‑based environments (Azure preferred)
• Strong ownership mindset and collaboration across teams

Responsibilities

• Contribute across all phases of the software development lifecycle within an Agile team
• Write well‑designed, testable, and efficient code following engineering best practices
• Tackle live production challenges, including troubleshooting and performance issues
• Participate in code reviews (PRs) and contribute as a strong team player
• Work closely with team leads, stakeholders, and partner teams across the organization

Skills

C#

.NET Core

ASP.NET Core

Distributed systems

Kafka

SQL

Azure

Education

Bachelor's degree in Computer Science or related field

Tools

GitHub

Visual Studio

VS Code

Rider

Docker

Kubernetes

TeamCity

Octopus

Job description

StoneX Group Inc. is seeking a Staff Software Engineer to join the API & Middleware Group in Winter Park, FL. You will design and operate high‑performance services, contribute to architecture, and drive reliability while collaborating with engineers, tech leads, and QA partners.

You will work with C#, .NET Core, Kafka, and cloud technologies, focusing on scalable middleware and core platform services used globally. The role offers an in‑office environment four days a week in Florida.