Freelance Full Stack Developer React Python Jobs in Washington

Full Stack Developer

Location: Hanover, MD- On-site

Type: Full-time

Clearance: No Clearance Required

Job Description

Eccalon is seeking a Full Stack Developer to design, build, and ship production software across a portfolio of DoD, Intelligence, and enterprise programs. You will own features end-to-end—from React front-ends and Next.js applications through Node.js/Python APIs and AWS-hosted data stores—and actively leverage LLM and AI-assisted development techniques to accelerate delivery and enhance product capabilities. You will work closely with cross-functional teams including DevOps, UX/UI design, and program leadership in a security-conscious, compliance-driven environment.

Responsibilities

• Design, develop, and maintain full-stack web applications from UI through API to data layer, with ownership of features across the entire delivery lifecycle.
• Build front-end architecture and UI components using React and Next.js; create reusable component libraries that support consistent UX across multiple products.
• Integrate LLM and AI capabilities into product features using the Anthropic API (Claude) and other model providers; apply prompt engineering, retrieval-augmented generation (RAG), and agentic workflow patterns to build intelligent, context-aware application experiences.
• Translate designs and wireframes into high-quality, accessible, responsive code; leverage AI-assisted development tools (e.g., Claude Code) to accelerate implementation without sacrificing quality or security.
• Develop and maintain back-end services and REST APIs using Node.js and Python; design for security, scalability, and compliance from the start.
• Integrate front-end applications with back-end APIs and AWS cloud services (Cognito, Lambda, API Gateway, DynamoDB, RDS/PostgreSQL); implement authentication flows including OAuth2/OIDC and JIT provisioning.
• Implement security and data protection measures aligned to NIST 800-171 and CMMC requirements; apply OWASP Top 10 mitigations and participate in code-level security reviews.
• Implement responsive, accessible UI designs (WCAG 2.1) that render consistently across devices and browsers.
• Write clean, well-tested, and well-documented code; contribute to and enforce engineering standards through trunk-based development and peer code review.
• Conduct thorough code reviews with a focus on security, maintainability, and AI-generated code validation; mentor junior engineers on best practices.
• Troubleshoot and debug complex issues across the full stack, including integration points with LLM APIs, cloud services, and third-party authentication providers.
• Design and manage relational and NoSQL data models across PostgreSQL, DynamoDB, and MongoDB; optimize queries and data access patterns for performance and cost.
• Apply structured prompt engineering techniques—chain-of-thought, few-shot examples, tool use, and system prompt design—to build reliable, production-ready LLM-powered features; evaluate and mitigate prompt injection, hallucination, and data leakage risks.
• Partner with UX/UI designers, product managers, and DevOps to deliver features end-to-end; translate program requirements into scalable technical solutions.
• Stay current on advancements in LLM/AI tooling, web frameworks, and cloud-native development; bring new techniques back to the team through demos, documentation, and knowledge sharing.

Required Qualifications

• Bachelor’s degree in Computer Science, or a related field (or equivalent work experience).
• 3+ years of experience as a Full Stack Developer shipping production web applications; experience in a DoD, federal contracting, or regulated environment a plus.
• Strong proficiency in HTML5, CSS3, JavaScript/TypeScript (ES6+), React, and Next.js; comfort building and documenting reusable component libraries.
• Proficiency in Node.js and Python for server-side development; experience with Express.js, Nest.js, and/or Next.js API routes.
• Hands-on experience integrating LLM APIs (Anthropic Claude, OpenAI, or similar) into production applications; demonstrated ability to write effective prompts, implement RAG pipelines, and build tool-use/agentic workflows.
• Experience with relational databases (PostgreSQL) and NoSQL databases (DynamoDB); comfort writing and optimizing queries and managing schema migrations.
• Solid understanding of RESTful API design, microservices architecture, and AWS services (API Gateway, Lambda, Cognito, S3, CloudFront).
• Proficiency with Git and trunk-based development workflows; experience with GitHub or GitLab for PR-based collaboration.
• Working knowledge of CI/CD pipelines (GitLab CI/CD) and cloud deployment practices on AWS; familiarity with security-focused DevSecOps gates.
• Strong analytical and problem-solving skills; ability to work independently across multiple concurrent projects and communicate technical decisions clearly to non-technical stakeholders.
• Comfort working in a regulated, compliance-aware environment; familiarity with NIST 800-171, CMMC, or FedRAMP requirements preferred.
• Strong interpersonal and communication skills; proven ability to collaborate effectively across engineering, design, DevOps, and program management teams.

Preferred Qualifications

• Experience building AI-powered features using RAG, vector databases (e.g., pgvector, Pinecone), or LLM orchestration frameworks (e.g., LangChain, LlamaIndex).
• Familiarity with model context protocol (MCP) patterns and structured tool-use design for LLM-integrated applications.
• Experience with Azure services (Azure AD, GCC High) or AWS GovCloud in a DoD or federal contracting environment.
• Familiarity with TypeScript across both front-end and back-end (Node.js/Next.js) codebases.
• Experience with Playwright or Cypress for end-to-end testing of web applications.
• Background in UX/UI collaboration with Figma or similar design tooling.

Equal Employment Opportunity (EEO) Policy

Eccalon provides equal employment opportunities to all employees and applicants for employment and prohibits discrimination and harassment of any type without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state, or local laws. This policy applies to all terms and conditions of employment, including recruiting, hiring, placement, promotion, termination, layoff, recall, transfer, leaves of absence, compensation, and training.