CSI Companies · 16 hours ago
Full Stack Developer Contractor
St Louis, MO
Contract
Onsite
Senior Level
$55/hr - $62/hr
6+ years expThe CSI Companies is a leading staffing and recruiting firm, and they are seeking an experienced Full Stack Developer Consultant with a strong focus on API development and web application delivery. This role involves designing, building, and deploying secure, scalable APIs and web applications while collaborating closely with cross-functional teams.
Staffing & Recruiting
Hiring Manager
John Hubbuch
Responsibilities
Design, develop, test, and deploy scalable RESTful APIs using Python and FastAPI
Build and maintain backend services supporting enterprise web applications
Collaborate with frontend teams to integrate APIs into web applications
Develop and maintain CI/CD pipelines using GitHub Actions and/or Azure DevOps
Apply secure development best practices, including OAuth2, JWT, and secure coding standards
Write clean, modular, and maintainable code with a strong emphasis on quality and performance
Develop and execute unit and integration tests
Participate in peer code reviews and enforce coding standards
Create and maintain technical documentation
Partner with product owners, architects, DevOps, and QA teams to deliver solutions
Support production deployments and ensure application stability
Qualification
Required
6+ years of professional software development experience
Strong proficiency in Python
Hands-on experience with FastAPI
Experience designing and developing RESTful APIs
Solid understanding of backend architecture and web application integration
Experience with Azure DevOps (ADO) and/or GitHub
Proven experience building and maintaining CI/CD pipelines
Knowledge of secure application development practices (OAuth2, JWT)
Foundation models (LLMs, multimodal models)
Prompting and instruction design
Context window limitations and management
Retrieval-Augmented Generation (RAG)
Embeddings and vector search
Fine-tuning vs adapters (e.g., LoRA)
Tool/function calling and system integration
Structured outputs (JSON/schema-based)
Model evaluation (accuracy, latency, cost, safety)
Hallucination mitigation strategies
AI safety, governance, and data handling best practices
Agent-based systems that plan, act, and iterate toward goals
Autonomy models and enterprise guardrails
Planning and task decomposition
Tool usage and action execution
Memory management (persistent vs ephemeral)
State tracking and workspace management
Reflection and verification loops
Multi-agent collaboration patterns
Human-in-the-loop (HITL) workflows
Observability, logging, and monitoring of agent behavior
Preferred
Experience working in large enterprise environments
Exposure to cloud-native or microservices architectures
Strong communication and collaboration skills
Ability to work onsite in a hybrid enterprise setting
Benefits
Weekly pay
Medical, dental, and vision coverage
Voluntary Life and AD&D coverage
Paid training
Opportunity for advancement based on performance and availability
Company
CSI Companies
Headquartered in Jacksonville, FL, CSI Companies partners with organizations nationwide to deliver solutions-focused workforce services.
51-200 employees
Funding
Current Stage
Growth StageLeadership Team
Chris Flakus
Chief Executive Officer
James Chiang
Chief Financial Officer
Recent News
Company data provided by crunchbase