Job#: 3021079 Job Description: We are hiring Senior Full Stack Developers! Role: Senior Full Stack Developer (Python)Supporting: Large Financial Services Client
Location: Onsite - McLean, VAPosition Description: We're seeking a highly skilled Senior Full Stack Developer with deep Python engineering expertise to drive the development, modernization, and optimization of complex, high-impact applications. In this role, you'll work on sophisticated data-centric systems, contribute to architectural enhancements, and solve challenging engineering problems involving large data sets, concurrency, and long-running batch processes.
You'll design and build clean, scalable services; refactor and enhance existing codebases; improve performance; and strengthen reliability across mission-critical applications. This is an ideal opportunity for a seasoned engineer who enjoys ownership, collaboration, and tackling meaningful technical challenges that influence large-scale systems. If you're ready to take the next step in your career and work on meaningful, high-impact systems, we encourage you to apply today.
Qualifications:- 5+ years of professional Python development across backend services and application engineering.
- Expertise with major Python libraries: Pandas, NumPy, Gunicorn, Celery, SQLAlchemy, Flask/FastAPI.
- Strong experience handling large data libraries, large currency datasets, and complex database interactions.
- Proven background with concurrency, distributed workloads, and managing multi-hour batch processes (cancel/restart/resume/status polling, efficient recovery, and scalability).
- Demonstrated ability to write high-quality, well-tested code: automated unit, integration, regression, and performance tests.
- Strong problem-solving skills, critical thinking, and comfort working in Agile environments.
- Graduate degree in Computer Science or related field is preferred.
- Experience in financial accounting, fixed income, or capital markets is huge plus.
- Familiarity with temporal.io is strongly preferred.
EEO Employer
Apex Systems is an equal opportunity employer. We do not discriminate or allow discrimination on the basis of race, color, religion, creed, sex (including pregnancy, childbirth, breastfeeding, or related medical conditions), age, sexual orientation, gender identity, national origin, ancestry, citizenship, genetic information, registered domestic partner status, marital status, disability, status as a crime victim, protected veteran status, political affiliation, union membership, or any other characteristic protected by law. Apex will consider qualified applicants with criminal histories in a manner consistent with the requirements of applicable law. If you have visited our website in search of information on employment opportunities or to apply for a position, and you require an accommodation in using our website for a search or application, please contact our Employee Services Department at or .
Apex Systems is a world-class IT services company that serves thousands of clients across the globe. When you join Apex, you become part of a team that values innovation, collaboration, and continuous learning. We offer quality career resources, training, certifications, development opportunities, and a comprehensive benefits package. Our commitment to excellence is reflected in many awards, including ClearlyRated's Best of Staffing in Talent Satisfaction in the United States and Great Place to Work in the United Kingdom and Mexico. Apex uses a virtual recruiter as part of the application process. Click for more details.
Apex Benefits Overview: Apex offers a range of supplemental benefits, including medical, dental, vision, life, disability, and other insurance plans that offer an optional layer of financial protection. We offer an ESPP (employee stock purchase program) and a 401K program which allows you to contribute typically within 30 days of starting, with a company match after 12 months of tenure. Apex also offers a HSA (Health Savings Account on the HDHP plan), a SupportLinc Employee Assistance Program (EAP) with up to 8 free counseling sessions, a corporate discount savings program and other discounts. In terms of professional development, Apex hosts an on-demand training program, provides access to certification prep and a library of technical and leadership courses/books/seminars once you have 6+ months of tenure, and certification discounts and other perks to associations that include CompTIA and IIBA. Apex has a dedicated customer service team for our Consultants that can address questions around benefits and other resources, as well as a certified Career Coach. You can access a full list of our benefits, programs, support teams and resources within our 'Welcome Packet' as well, which an Apex team member can provide.
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