Government Software Developer Jobs in California

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Lawrence Livermore National Laboratory (LLNL) has turned bold ideas into world-changing impact advancing science and technology to strengthen U.S. security and promote global stability. 

Our mission spans four critical national security areas nuclear deterrence, threat preparedness, energy security, and multi-domain defense empowering teams to take on the toughest challenges of today and tomorrow. With a culture built on innovation and operational excellence, LLNL is a place where your expertise can make a real impact.

The Conflict Simulation Laboratory (CSL) of the Global Security Computing Applications Division (GS-CAD) within the Computation Directorate has an opening for a Software Developer specializing in the analysis, design, development, and implementation of C++ scientific software.  The CSL develops and deploys the Joint Conflict and Tactical Simulation (JCATS) and JCATS Low Overhead Driver (JLOD) simulation suites to users around the world. The CSL works closely with external partners to enable JCATS and JLOD to interoperate with other simulation models and tools in a federated environment.

JCATS and JLOD are tactical simulations that model soldiers, tanks, and other military platforms maneuvering in 3D environments. Line of sight, projectile paths, collision detection, and many other algorithms calculate real time results for military trainers and analysts. You will analyze, design, and implement new functionality using object-oriented, C++ programming and object-oriented algorithms, while balancing performance tradeoffs.  CSL simulation products are used for training and analysis by 30 countries, the Departments of Energy and War, and other government agencies. Their applications include military operations, peacekeeping, drug interdiction, homeland defense, site security, and civil defense preparation. You will interact with team members, project management, sponsors, and users. The position will report to the E/CSL Associate Program Leader.

This position will be filled at either the SES.1 or SES.2 level based on knowledge and related experience as assessed by the hiring team. Additional job responsibilities (outlined below) will be assigned if hired at the higher level.

This position requires full time onsite presence.

In this role, you will

• Develop object-oriented software packages and applications using the C++ programming language in a Linux environment.
• Actively participate in all phases of object-oriented product development; analysis, design and implementation; to include direct interactions with sponsors and other modeling agencies.
• Create documentation for users on new and existing products and processes.
• Occasional direct customer technical support and interactions with JCATS exercise operations support personnel.
• Provide occasional field development and integration with outside models.
• Occasional foreign and/or domestic travel.
• Perform other duties as assigned.
• Build and support production releases of desktop applications used by customers around the world.
• Perform other duties as assigned.

Additional job responsibilities, at the SES.2 level 

• Provide remote and on-site SME technical support for various customers.
• Work closely with CSL staff and external customers to identify and develop simulation software requirements.
• Assume lead role for one or more simulation model functional areas with responsibility for requirements vetting, design development and reviews, software implementation, documentation, and testing verification.

• Ability to secure and maintain a U.S. DOE Q-level security clearance which requires U.S. citizenship 
• BS in Computer Science, Engineering, Mathematics or equivalent level of demonstrated knowledge.
• Demonstrated fundamental experience designing, implementing, and debugging production-quality C++ applications, using modern C++ standards and object-oriented designs
• Demonstrated object-oriented analysis, design and implementation skills.
• Fundamental knowledge and experience developing applications in a Linux/UNIX environment.
• Ability to work in a highly interactive software development team.
• Effective verbal and written communication and interpersonal skills necessary to effectively collaborate in a team environment.

Additional qualifications at the SES.2 level

• Ability to work effectively with minimal guidance.
• Broad experience developing production-quality C++ applications
• Experience providing innovative approaches and applying new technologies to broadly defined tasks and projects.
• Broad experience applying effective analytical and problem-solving skills to moderately complex problems.

Qualifications We Desire

• MS in Computer Science, Engineering, Mathematics.
• Knowledge and experience with event-based software simulations.
• Experience developing complex, client/server software suites.
• Experience developing object-oriented GUIs, including the use of OpenGL.
• Knowledge of plane and solid geometry and vector analysis.
• Knowledge of military operations.

Pay Range

$121,830 - $185,544 Annually

$121,830 - $154,500 Annually for the SES.1 level

$146,340 - $185,544 Annually for the SES.2 level

This is the lowest to highest salary we in good faith believe we would pay for this role at the time of this posting; pay will not be below any applicable local minimum wage.  An employee's position within the salary range will be based on several factors including, but not limited to, specific competencies, relevant education, qualifications, certifications, experience, skills, seniority, geographic location, performance, and business or organizational needs.

#LI-Onsite

Position Information

This is a Flexible Term appointment, which is for a definite period not to exceed six years.  If final candidate is a Career Indefinite employee, Career Indefinite status may be maintained (should funding allow).

Why Lawrence Livermore National Laboratory?

• Included in 2026 Best Places to Work by Glassdoor!
• Flexible Benefits Package
• 401(k)
• Relocation Assistance
• Education Reimbursement Program
• Flexible schedules (*depending on project needs)
• Our values - visit https://www.llnl.gov/inclusion/our-values

Security Clearance

This position requires a Department of Energy (DOE) Q-level clearance.  If you are selected, we will initiate a Federal background investigation to determine if you meet eligibility requirements for access to classified information or matter. Also, all L or Q cleared employees are subject to random drug testing.  Q-level clearance requires U.S. citizenship. 

Pre-Employment Drug Test

External applicant(s) selected for this position must pass a post-offer, pre-employment drug test. This includes testing for use of marijuana as Federal Law applies to us as a Federal Contractor.

Wireless and Medical Devices

Per the Department of Energy (DOE), Lawrence Livermore National Laboratory must meet certain restrictions with the use and/or possession of mobile devices in Limited Areas. Depending on your job duties, you may be required to work in a Limited Area where you are not permitted to have a personal and/or laboratory mobile device in your possession.  This includes, but not limited to cell phones, tablets, fitness devices, wireless headphones, and other Bluetooth/wireless enabled devices.  

If you use a medical device, which pairs with a mobile device, you must still follow the rules concerning the mobile device in individual sections within Limited Areas.  Sensitive Compartmented Information Facilities require separate approval. Hearing aids without wireless capabilities or wireless that has been disabled are allowed in Limited Areas, Secure Space and Transit/Buffer Space within buildings.

How to identify fake job advertisements

Please be aware of recruitment scams where people or entities are misusing the name of Lawrence Livermore National Laboratory (LLNL) to post fake job advertisements. LLNL never extends an offer without a personal interview and will never charge a fee for joining our company. All current job openings are displayed on the Career Page under "Find Your Job" of our website. If you have encountered a job posting or have been approached with a job offer that you suspect may be fraudulent, we strongly recommend you do not respond.

To learn more about recruitment scams: https://www.llnl.gov/sites/www/files/2023-05/LLNL-Job-Fraud-Statement-Updated-4.26.23.pdf

Equal Employment Opportunity

We are an equal opportunity employer that is committed to providing all with a work environment free of discrimination and harassment. All qualified applicants will receive consideration for employment without regard to race, color, religion, marital status, national origin, ancestry, sex, sexual orientation, gender identity, disability, medical condition, pregnancy, protected veteran status, age, citizenship, or any other characteristic protected by applicable laws.

Reasonable Accommodation

Our goal is to create an accessible and inclusive experience for all candidates applying and interviewing at the Laboratory.  If you need a reasonable accommodation during the application or the recruiting process, please use our online form to submit a request. 

California Privacy Notice

The California Consumer Privacy Act (CCPA) grants privacy rights to all California residents. The law also entitles job applicants, employees, and non-employee workers to be notified of what personal information LLNL collects and for what purpose. The Employee Privacy Notice can be accessed here.