Demo

Senior Application Developer (onsite)

System One
Washington, DC Contractor
POSTED ON 4/8/2026
AVAILABLE BEFORE 7/5/2026

Sr. Application Developer
Washington, DC - onsite
Candidates must be able to work without sponsorship

Position Description:

• This position will help support the development of services utilizing AWS Containerized and cloud services along with familiarity with Agile processes and roles along with experience utilizing CI/CD for building and deploying cloud applications with the Python language for backend services and Angular for front-end development.
• The candidate must be able to lead one or more of the following: database management, programming, cloud security/recovery, and cloud-centric integration.
• The candidate should be able to contribute to the design of the code they will be responsible for implementing along with the required documentation.
• The candidate will be responsible for remediation and unit testing of code when issues arise as part of the CI/CD, application development, and user deployment process.
• The candidate should have experience working effectively as part of an Agile team.

Work Experience:
• AWS DevOps & Systems Engineering:

o Proficiency in Terraform includes the ability to create, secure, manage, update, and maintain AWS GovCloud-native infrastructure including services like: Glue, RDS/Aurora (Postgres), CloudWatch, CloudTrail, S3, ECS, API Gateway, etc.
o Proficiency in infrastructure-as-code DevOps using Terraform including CI/CD, automated testing, and other SRE & DevOps best practices
o Understanding of and experience with central log aggregation using CloudWatch or SPLUNK. Experience implementing and supporting a solution’s logging and auditing capabilities to support enterprise or legal retention and auditing requirements.
o At least 3 years of experience in a role with mid- or senior-level operational responsibility of an AWS-native solution, preferably GovCloud. Experience should include operations, maintenance (e.g., update/release/patch management), tuning, troubleshooting, and other SRE/Systems Engineering tasks. Understanding of monitoring, operational responsibility (e.g., on-call rotation), change control, and production operations. Preferably including federal experience and understanding of NIST 800.53 (FISMA).
• AWS Data Engineering:
o Proficiency in developing, maintaining, monitoring, and the long-term operations of data pipelines or processing systems running in AWS, preferably GovCloud. Understanding of data replication, extraction, transformation, loading, and performance tuning of solutions utilizing multiple streams of input data —e.g., ETL to RDBMS. Preferably using code-based, git and DevOps-enabled technologies using Python or SQL such as PySpark, pandas, or dbt.
o Proficiency in AWS Data Pipeline technologies including either Glue or Airflow; RDS Postgres and/or Aurora Postgres, Aurora/S3.
o Proficiency in developing, developing against, and testing REST or GraphQL API’s. Experience supporting an API in production used by a user-facing web application. Understanding of API testing, best practices, and the AWS API ecosystem: API Gateway, Lambda, etc.
o Proficiency in DevOps include CI/CD, automated testing, and other DataOps best practices.
o Understanding of and experience with data quality and other data pipeline automated testing such as Glue Data Quality or Great Expectations.
o At least 3 years of experience as a mid- or senior-level data engineer with operational responsibilities in AWS, preferably GovCloud. Understanding of monitoring, operational responsibility (e.g., on-call rotation), change control, and production systems operations. Preferably including federal experience and understanding of NIST 800.53 (FISMA).
• AWS Front-End Engineer:
o Proficiency in developing, supporting, and maintaining API-based web applications using Angular or React in Typescript.
o Proficiency in developing and testing REST or GraphQL API’s. Experience supporting an API in production used by a user-facing web application. Understanding of API testing, best practices, and the AWS API ecosystem: API Gateway, Lambda, etc.
o Proficiency in DevOps including CI/CD, automated testing with Selenium, and other SRE & DevOps best practices.
o Proficiency in creating highly interactive, data-driven applications for users to view, correct, manipulate, and process tabular data from multiple sources. Should include complex, interactive elements using packages such as Highcharts, ag-grid, or Plotly.
o Proficiency in developing, supporting, and maintaining Angular applications.
o Proficiency in modern authentication and authorization standards such as OpenId Connect and OAuth 2.0. Experience in integrating web applications with Okta, JWT, AWS services such as IAM and Verified Permissions.
o Proficiency in automated testing frameworks including Jasmine and Selenium.
o Preferred: Experience with and understanding of mapping and geospatial data (e.g., geocoding). Experience with ESRI Online, creating interactive maps, etc.

Technical Skills:
• Bachelor’s degree in computer science, information technology, or related field, and six years of experience
• Amazon Web Services (AWS)
o ECS
o Terraform
o AWS CloudTrail
o AWS CloudWatch
o AWS API Gateway and AWS Load Balancer
o AWS S3
o AWS RDS or Aurora, PostgreSQL
o AWS Lambda
o AWS Glue or MWAA (Airflow)
o AWS GovCloud experience is a plus
• DevOps
o GitLab (or Argo CD)
o git, CI/CD automation
o Unit testing
o Automated testing
• Authentication and Authorization
o Okta
o OAuth 2.0
o OpenID Connect (OIDC)
• Containerization
o Docker
o Kubernetes (AWS EKS, ECS, or Fargate preferred)
• Front-End Development
o Typescript
o Angular
o REST (or GraphQL) API
o Selenium
o Postman
o Swagger (OpenAPI)
o Using Okta for application authentication, JWT
• Data Engineering
o AWS Glue or MWAA (Airflow)
o Python 3.x data engineering with pandas or SPARK
o Data Quality testing tooling (e.g., Great Expectations, Glue Data Quality)
• Data Visualization
o Highcharts
o Ag-grid
o Plotly
• XACTA 360 is a plus
• SPLUNK is a plus
• Experience working with Federal Agencies and with the NIST 800.53 FISMA standard and process is a plus


System One, and its subsidiaries including Joulé and 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.

#M-
#LI-



Ref: #851-Rockville-S1

Hourly Wage Estimation for Senior Application Developer (onsite) in Washington, DC
$52.00 to $66.00
If your compensation planning software is too rigid to deploy winning incentive strategies, it’s time to find an adaptable solution. Compensation Planning
Enhance your organization's compensation strategy with salary data sets that HR and team managers can use to pay your staff right. Surveys & Data Sets

What is the career path for a Senior Application Developer (onsite)?

Sign up to receive alerts about other jobs on the Senior Application Developer (onsite) career path by checking the boxes next to the positions that interest you.
Income Estimation: 
$120,936 - $155,014
Income Estimation: 
$131,745 - $167,716
Income Estimation: 
$144,503 - $184,592
Income Estimation: 
$102,541 - $137,871
Income Estimation: 
$153,752 - $200,235
Income Estimation: 
$92,369 - $122,605
Income Estimation: 
$117,024 - $149,811
Employees: Get a Salary Increase
View Core, Job Family, and Industry Job Skills and Competency Data for more than 15,000 Job Titles Skills Library

Job openings at System One

  • System One Arlington, VA
  • We are seeking an experienced Construction Project Manager to lead and deliver complex industrial construction projects . This role is primarily focused on... more
  • 8 Days Ago

  • System One Point, NY
  • Job Title: Sr. Network Engineer Location: Kings Point, NY (Onsite) Type: W2 Contract Compensation: $50.00 - $60.00 hourly Contractor Work Model: Hybrid (3 ... more
  • 8 Days Ago

  • System One Moscow, ID
  • Mountain Ltd. has an opening for an OSP Engineer working in the Moscow , ID area. Since 1979, Mountain Ltd. has successfully created and supported turnkey ... more
  • 8 Days Ago

  • System One Falls, ID
  • Mountain Ltd. has an opening for an OSP Field Engineer in the Twin Falls, ID area! Since 1979, Mountain Ltd has successfully created and supported turnkey ... more
  • 8 Days Ago


Not the job you're looking for? Here are some other Senior Application Developer (onsite) jobs in the Washington, DC area that may be a better fit.

  • Jobs via Dice Washington, DC
  • Dice is the leading career destination for tech experts at every stage of their careers. Our client, System One, is seeking the following. Apply via Dice t... more
  • 8 Days Ago

  • Clark Construction Group Mc Lean, VA
  • The Senior Application Developer is responsible for ensuring the stability, support, and continuous modernization of critical enterprise applications that ... more
  • 9 Days Ago

AI Assistant is available now!

Feel free to start your new journey!