Freelance Java Backend Developer Jobs in Colorado

If you've been building your skills in backend development, objectoriented programming, and missiondriven engineering, and you're ready for work that actually moves the needle, this is the kind of opportunity cleared engineers pursue when they want to grow while making real impact. If you take pride in your craft, enjoy solving meaningful technical problems, and want your work to support a mission with visibility at senior levels, you'll thrive here.

We're hiring a Backend Software Engineer to support a highvisibility, datadriven application used across the organization for analytics and reporting. You'll help build and maintain core backend services, develop RESTful APIs, support datadriven functionality, and contribute to ongoing system enhancements within a Linuxbased environment. Your work will directly support system reliability, performance, and data accuracy for mission stakeholders. Our primary development team operates out of Gaithersburg, MD, but we also support onsite engineers in Chantilly, VA, Alexandria, VA; Aurora, CO; St. Louis, MO; and Tucson, AZ, giving top talent multiple paths to join the mission.

And while the requisition requirements may seem standard fare, the position is not; as it will join a high performing team that is changing the way digital engineering and mission operations intelligence is enabled for our customer.

Why This Role Stands Out

• High Impact: Your work supports a widely used application that drives realtime decisionmaking
• High Visibility: Collaborate with engineering teams and mission stakeholders across programs
• Career Growth: Build deeper expertise in backend development, API design, and scalable systems
• Challenging Work: Contribute to complex backend features - not routine maintenance tasks

Essential Responsibilities

• Backend Development:Design, develop, test, and maintain backend application components using Java or Python
• REST API Development:Develop and maintain RESTful services to support application functionality and system integrations
• Object-Oriented Programming:Apply object-oriented design principles to build scalable and maintainable systems
• Database Development:Write and modify SQL queries to support application functionality and data retrieval
• Data Source Collaboration: Collaborate with internal and external teams to understand data sources, formats, and access methods, and support integration into backend systems
• Linux Environments:Develop and troubleshoot applications within Linux-based environments
• Data Processing & Business Logic:Implement backend logic for data transformation, processing, and system workflows
• Bug Fixing & Enhancements:Identify, debug, and resolve application-level defects and performance issues
• Code Quality:Follow coding standards, participate in code reviews, and support documentation efforts

Basic Qualifications

• Bachelor's degree in Computer Science, Software Engineering, or a related field with 4-8 years of experience; or a Master's degree with 2-6 years of experience
• US Citizenship
• Active TS/SCI with the ability to successfully pass a Polygraph
• Professional experience developing objectoriented applications in Java or Python
• Handson experience building and maintaining RESTful APIs
• Basic to moderate experience with SQL capability, including writing queries and working with relational databases
• Working knowledge of Linuxbased environments
• Ability to work independently on defined tasks within established technical frameworks and deliver reliable results

Preferred Qualifications

• Experience withApache Airflow or similar workflow orchestration technologies
• Experience withSpring Boot, Django, or similar backend frameworks
• Exposure toCI/CD pipelines (GitLab, Jenkins, etc.)
• Familiarity withcontainerization (Docker, OpenShift)
• Exposure tocloud environments (AWS or Azure)
• Experience working inAgile development environments

#MARU

If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo - because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 - and moving faster than anyone else dares.

Original Posting:April 16, 2026Pay Range:Pay Range $87,100.00 - $157,450.00

The Leidos pay range for this job level is a general guideline onlyand not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.