Mid-level Full Stack Developer (Typescript)

We are seeking a talented and motivated Mid-Level Full Stack Developer to join our engineering team. In this role, you will design, develop, and maintain end-to-end web applications using modern JavaScript/TypeScript technologies across the stack. You will collaborate closely with product managers, designers, and fellow engineers to deliver scalable, high-quality, visually polished software that delivers real value to our users.

Candidate MUST:

Be a U.S. citizen or Green Card holder (Permanent Resident) who is currently located in the United States for the current three consecutive years, with the Ability to obtain a level 4 Public Trust Clearance.

*Preference for candidates who are local to the Washington, DC, VA and MD areas.

Key Responsibilities

• Design, develop, test, and deploy full-stack web applications using modern JavaScript/TypeScript frameworks (React, Angular, Node.js) across the frontend and backend.

• Build and maintain RESTful APIs and serverless/microservice components that are secure, performant, and well-documented.

• Develop responsive, user-friendly, and visually compelling interfaces following UX/UI best practices and accessibility standards (Section 508 compliance).

• Build and maintain Azure Static Web Apps and integrate with headless CMS platforms (e.g., Payload, Contentful, Strapi, Sanity, Sitecore, or similar) to power content-driven experiences.

• Implement and follow GitHub Flow branching strategies and GitOps practices for reliable, traceable deployments.

• Leverage GitHub Copilot to accelerate development while maintaining code quality and ownership.

• Use GitHub Codespaces for consistent, cloud-based development environments across the team.

• Integrate and act on findings from GitHub Advanced Security (CodeQL, secret scanning, Dependabot) to keep applications secure by default.

• Participate in code reviews, providing constructive feedback and learning from peers.

• Work with relational (PostgreSQL, MySQL) and/or NoSQL (MongoDB, Redis) databases — designing schemas, writing efficient queries, and optimizing performance.

• Collaborate in an Agile/Scrum environment, contributing to sprint planning, stand-ups, and retrospectives.

• Troubleshoot, debug, and resolve production issues across the full stack.

• Contribute to CI/CD pipelines (GitHub Actions) and participate in deployment activities.

• Mentor junior developers and share knowledge through documentation and tech talks.

Required Qualifications

• Bachelor's degree in Computer Science, Software Engineering, or a related field (or equivalent practical experience).

• Minimum of 4 years of professional software development experience.

• Strong proficiency in JavaScript (ES6+) and TypeScript across both frontend and backend (Node.js).

• Hands-on experience with at least one modern frontend framework: React or Angular.

• Solid understanding of HTML5, CSS3, and modern responsive design techniques.

• Design-heavy experience with a portfolio of public-facing sites that demonstrates strong visual design sensibility, attention to detail, and user-centered thinking.

• Experience designing and consuming RESTful APIs; familiarity with JSON and HTTP standards.

• Proficiency with SQL and experience with relational databases (PostgreSQL or MySQL).

• Experience with Git and GitHub Flow workflows on GitHub.

• Understanding of Agile methodologies and tools (Jira, Confluence).

Highly Preferred Qualifications

• Experience building and deploying Azure Static Web Apps.

• Hands-on experience with a headless CMS (Contentful, Strapi, Sanity, Sitecore, or similar).

• Familiarity with Azure cloud services.

• Experience with CI/CD using GitHub Actions and applying GitOps principles.

• Practical use of GitHub Copilot in day-to-day development.

• Experience working in GitHub Codespaces or similar cloud development environments.

• Familiarity with GitHub Advanced Security (CodeQL, secret scanning, Dependabot alerts).

• Exposure to NoSQL databases (MongoDB, DynamoDB, Redis).

• Familiarity with infrastructure-as-code (Bicep, Terraform, or ARM templates).

• Experience with accessibility testing tools and remediation for Section 508 / WCAG 2.1 AA compliance.

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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.

The Leidos pay range for this job level is a general guideline only and 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.