Senior Software Engineer

WHO WE ARE

Apex Fintech Solutions (Apex) powers innovation and the future of digital wealth management by building tech-forward solutions that help simplify, automate, and facilitate access to financial markets for all. Our robust suite of fintech software enables us to support clients such as Stash, Betterment, SoFi, Webull, and eToro, amongst many others; collectively, Apex powers access to the stock market for over 22+ million end customers.

At Apex, we are changing how the securities industry operates by reinventing the status quo, which was manual, slow, and accessible only by the ultra-wealthy. We re digitizing and democratizing systems so that everyone has an opportunity to invest.

When you re at Apex, you drive this change. You re part of a global team with a clear vision: to be the trusted technology that powers the digital economy. Our offices in Austin, Dallas, Chicago, New York, Portland, Belfast, and Manila are home to over 1,000 employees.

Together, we re shaping the future of financial innovation. Embrace change. Solve big. Win together. And be G.R.E.A.T. — grit, results, empathy, accountability, and teamwork — with Apex.

We re proud to be recognized for the innovative work we do, the purpose-driven nature of our work, and the collaborative culture we ve created. Here are just a few of the many awards we ve recently received:

Best Places to Work 2026, 2025, 2024, 2023
Presented by Built In

Wealth Tech of the Year
2025
Presented by US Fin Tech Awards

The World s Top 250 Fintech Companies
2024
Presented by CNBC

Apex Fintech Solutions is seeking a Senior Software Engineer to play a key role on our Billing engineering team, responsible for designing, developing, and maintaining high-quality software solutions. You will leverage your experience and expertise to contribute to the software development lifecycle, from requirements analysis and implementation to testing and deployment. You will collaborate with team members and cross-functional partners to deliver scalable, reliable, and efficient software products that meet the needs of our users and business objectives.

• Build and maintain microservices within the billing platform, including calculation, rates, settlement, and charge services, writing production-quality Java code that handles complex financial workflows and data processing
• Own end-to-end delivery of features from design through deployment, implementing rate configurations, charge calculation logic, settlement generation, and integrations with external systems like Big Query and third-party financial platforms
• Optimize performance-critical code paths for high-volume billing operations, utilizing Postgre
  
  SQL with jOOQ, implementing caching strategies, and ensuring efficient data processing for large-scale financial calculations
• Write comprehensive tests and ensure code quality, maintaining high test coverage across unit, integration, and end-to-end tests using the Bazel build system and established testing frameworks
• Collaborate with team members on technical design and code reviews, contributing to API design with gRPC and Protobuf, database schema migrations with Flyway, and event-driven architectures using Pub Sub
• Debug and resolve production issues, leveraging Datadog monitoring, logs, and metrics to investigate and fix issues in billing calculations, settlement processes, and service integrations
• Contribute to technical improvements and best practices within the team, sharing knowledge about billing domain logic, system architecture patterns, and development workflows with peers

• Bachelor s degree in Computer Science, Engineering, or related field (or equivalent work experience) required; advanced degree preferred
• 5+ years of experience in software development with a strong proficiency in one or more programming languages, including Java, Python
• Experience with automated testing frameworks and methodologies for backend services
• Experience contributing topics and participating in technical direction and implementation strategy for projects
• Experience with CI/CD (Continuous Integration/Continuous Deployment) pipelines and…