Senior Full Stack Engineer

System One; Reston (VA); Hybrid; USD 120,000 - 160,000; Full time

Job summary

System One is seeking a Senior Full Stack Engineer in Reston to drive performance-focused development across Java backend and frontend components. You will work within a hybrid model, combining on-site and remote collaboration to optimize applications and services in AWS.

The role emphasizes performance testing, bottleneck analysis, and data-driven remediation across microservices, databases, and cloud configurations. Strong communication and problem-solving are essential.

Qualifications

• 5+ years of full stack software engineering experience with hands-on development and troubleshooting.
• Strong Java development skills for backend services, APIs, and performance tuning.
• Hands-on performance engineering experience with test scripts.

Responsibilities

• Develop and execute end-to-end performance tests and analyze bottlenecks.
• Investigate performance issues and implement remediation.
• Tune Java applications, optimize PostgreSQL queries, review AWS configs.
• Retest after remediation and provide data-driven recommendations.

Skills

Java backend development

Performance tuning

Performance testing

Troubleshooting

Communications

Root-cause analysis

System optimization

AWS

Distributed systems

Frontend basics

Education

Bachelor's degree in computer science or related field

Tools

JMeter

LoadRunner

Gatling

Dynatrace

Splunk

CloudWatch

Job description

Job Title: Senior Full Stack Engineer
Location: Reston, Utah
Type: Permanent Full Time
Work Model: Hybrid – onsite and remote

Responsibilities

• Develop and execute end-to-end performance tests, analyze application behavior, and identify bottlenecks across integrated systems, microservices, databases, and AWS services.
• Investigate performance issues beyond the testing layer, determine root causes, and recommend or implement appropriate remediation.
• Tune and refactor Java applications, optimize PostgreSQL queries, review AWS configurations, and work across application components to improve overall system performance.
• Retest after remediation to validate improvements and provide clear, data-driven recommendations for additional changes.

Requirements

• 5+ years of full stack software engineering experience with hands-on development, troubleshooting, and application improvement.
• Strong Java development skills, especially for backend services, APIs, and performance tuning.
• Hands-on performance engineering experience, including developing, maintaining, and executing performance and load test scripts.
• Ability to identify performance bottlenecks across systems, microservices, APIs, databases, and cloud services.
• Strong troubleshooting and root cause analysis skills, with the ability to translate findings into actionable remediation recommendations.
• Experience profiling and refactoring application code to address performance, scalability, and resource utilization issues.
• Strong PostgreSQL and SQL skills, including query analysis, execution plans, indexing, and database performance tuning.
• Hands-on experience with AWS, including investigating and tuning application and cloud configurations affecting performance.
• Experience with microservices and distributed applications, including tracing transactions and dependencies across services.
• Experience with performance testing and application monitoring tools such as JMeter, LoadRunner, Gatling, Dynatrace, Splunk, CloudWatch, or comparable technologies.
• Ability to establish performance baselines, analyze test results and application metrics, implement or recommend remediation, and retest to demonstrate improvement.
• Working knowledge of front-end technologies to investigate performance issues across the full application stack.
• Strong communication skills to explain performance findings, root causes, and remediation recommendations to development and technical teams.
• Financial services or other large-scale, highly regulated enterprise application experience is preferred.
• Educational Requirements: Bachelor's degree in computer science, Information Systems, Software Engineering, or a related field.

System One, and its subsidiaries including Mountain Ltd., are leaders in delivering outsourced services and workforce solutions across North America. We help clients get work done more efficiently and economically, without compromising quality. System One not only serves as a valued partner for our clients, but we offer eligible employees health and welfare benefits coverage options including medical, dental, vision, spending accounts, life insurance, voluntary plans, as well as participation in a 401(k) plan.

System One is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, age, national origin, disability, family care or medical leave status, genetic information, veteran status, marital status, or any other characteristic protected by applicable federal, state, or local law.

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