Frontend Software Engineer Jobs in Denver, CO (NOW HIRING)

About Four Sea Group, Inc.

Four Sea Group is a 100% employee-owned technical mission support company based in Denver, Colorado. Founded by an aerospace industry veteran and PhD astrophysicist, we support complex defense, space, software, systems, and mission-focused programs for government and industry partners. What sets FSG apart is the caliber of our people and the way we operate: we are a reputation-driven team of highly skilled engineers and technical experts who are brought in for their depth, judgment, and ability to solve difficult problems. As an employee-owned company, we have built our compensation, benefits, and culture around a simple idea: when the company succeeds, that value should go back to the people doing the work.

Four Sea Group is seeking a Software Engineer specializing in front-end web development to create accessible, reliable, and user-centered applications that support secure customer missions.

As part of the Four Sea Group engineering team, this role will help translate complex mission and user requirements into effective digital experiences. The engineer will contribute to reliable program delivery by independently developing frontend capabilities, integrating them with backend services, and supporting the routine release of high-quality software in an Agile environment.

This position also contributes to Four Sea Group's broader technical capability by applying modern development practices, identifying practical open-source solutions, and collaborating across software, systems, integration, and test teams. The ideal candidate combines strong frontend implementation skills with sound technical judgment, adaptability, and a commitment to building software that is usable, maintainable, accessible, and aligned with customer needs.

• Bachelor's degree in Computer Science, Software Engineering, Computer Engineering, or a related technical field, or equivalent practical experience.
• Typically four or more years of relevant software engineering or frontend web development experience.
• Active Top Secret clearance at the time of hire, with the ability to obtain and maintain TS/SCI access with a CI Poly.
• Experience developing and deploying user-facing web applications using modern frontend development tools, techniques, and methods.
• Experience with HTML5, CSS3, responsive design, and CSS frameworks or preprocessors such as LESS, SASS, Bootstrap, Bourbon, or comparable technologies.
• Experience developing applications with Angular or React, and/or experience developing Java-based services.
• Experience integrating and consuming RESTful APIs.
• Experience creating functional web layouts from static designs, images, wireframes, or comparable design materials.
• Experience creating views or templates within full-stack frameworks such as Rails, Express, Django, or comparable technologies.
• Experience using Git and GitHub, GitLab, or a comparable version-control and collaborative development platform.
• Experience working in an Agile or Lean software development environment and supporting routine delivery of software changes.
• Knowledge of Section 508 requirements and experience developing accessible user interfaces.
• Experience evaluating and applying open-source solutions.
• Ability to independently deliver defined frontend features, troubleshoot implementation issues, and contribute to design decisions.
• Ability to quickly research and learn new programming tools, frameworks, and techniques.
• Strong written and verbal communication skills.
• Ability to work in-person (no virtual or hybrid options available) in Littleton, CO

• Active TS/SCI with CI Poly
• Experience supporting software development in a secure, government, defense, intelligence, or mission-critical environment.
• Experience with automated testing and continuous integration or continuous deployment practices.
• Experience with Jenkins, Puppet, or comparable build, deployment, or configuration-management tools.
• Experience with Docker, Kubernetes, or other containerization and orchestration technologies.
• Experience with data-visualization libraries such as D3.
• Experience with Java service development in a distributed or service-oriented environment.
• Experience with SAFe or another scaled Agile framework.
• Experience contributing to or engaging with open-source development communities.

The salary range for this role is $134,000.00 - $181,000.00 per year. The salary range provided is a good faith estimate representative of all experience levels. Four Sea Group, Inc. considers several factors when extending an offer, including but not limited to, the role, function and associated responsibilities, a candidate's work experience, location, education/training, key skills, and market conditions.

This position is expected to remain open through September 30, 2026. The company may adjust this deadline based on business needs and will update the posting as appropriate.

FSG is 100% ESOP-owned, which means our employees share directly in the company's growth. We offer competitive compensation, a strong employer-funded retirement plan, generous PTO and flexible time-off options, comprehensive health, dental, vision, life, short-term disability, and long-term disability benefits, plus a generous medical stipend that gives employees more choice and flexibility. Our model is intentionally built to keep more value with employees through salary, retirement, benefits, and ownership. You will work alongside experienced engineers and technical leaders on meaningful defense, space, software, systems, and mission support work, with room to grow as a technical expert, mentor, program contributor, or future leader.

Four Sea Group is an equal opportunity employer and considers qualified applicants for employment without regard to race, color, sex, sexual orientation, gender identity or expression, religion, national origin, marital or familial status, age, disability, veteran status, militaryserviceor application for military service.