David K.
Senior Software Engineer
Experience
Oct 2022 - Aug 2025
2 years 11 monthsSenior Software Engineer
Brainreader A/S
- Built secure backend services in Nest.js and Python (FastAPI) to process sensitive healthcare data, ensuring HIPAA-compliant storage and fast API performance.
- Developed patient dashboards and mobile wellness features using React, Next.js, and React Native, optimizing cross-platform usability for clinical and user-facing apps.
- Built a streaming chat UI with MUI in React/Next.js and React Native Paper while cutting UI build time 40% and improving task completion 20% across clinician workflows.
- Implemented secure JWT and OAuth2 authentication flows with RBAC for role-based access across dashboards, APIs, and mobile platforms.
- Shipped an LLM-powered symptom checker (OpenAI + LangChain, RAG on clinical notes) that reduced triage time 30% and increased self-serve resolutions significantly.
- Designed REST and GraphQL APIs with strict validation and clear versioning, enabling smooth frontend integration and reliable data flow between systems.
- Used TypeORM and SQLAlchemy to model patient records, health events, and permissions, supporting migrations and relational integrity in PostgreSQL.
- Optimized prompts, caching, and batching; lowered monthly token spend ~25% while keeping medical guidance accuracy within policy thresholds.
- Reduced backend response time by 40% through async job queues, caching with Redis, and refactoring API bottlenecks in high-traffic modules.
- Architected schemas in PostgreSQL and MongoDB and Elasticsearch for storing structured and unstructured medical data, including lab results, appointments, and logs.
- Deployed services on AWS and Azure using Docker, S3, Lambda, and Blob Storage, ensuring scalability, data privacy, and high availability.
- Set up GitHub Actions and Terraform pipelines to automate tests, builds, and secure deployments across dev, staging, and production.
- Led cross-functional sprints with product, design, and data teams, mentored juniors, and translated technical goals into user-centered outcomes in fast-moving environments.
Mar 2020 - Aug 2022
2 years 6 monthsSenior Software Engineer
Accedia
- Built high-throughput backend pipelines by migrating legacy NodeJS to Django, and Celery to power task queues and annotation flows across massive, distributed datasets.
- Created custom React hooks to handle forms, API calls, and UI logic, making the code cleaner and helping the team build features faster.
- Integrated third-party SSO providers Google and Auth0 to enable seamless login and centralized access control across teams and datasets.
- Built AI-powered pipelines with LangChain and LangGraph to automate data labeling workflows, combining human-in-the-loop checks, confidence scoring, and scalable orchestration and cut review time by 50%.
- Structured flexible data schemas using Prisma, SQLModel and Elasticsearch to handle millions of records, including raw inputs, metadata, and annotation revisions.
- Used React Query + visualized AG-Grid on large datasets to handle data fetching with smart caching, background updates, and batching, keeping the UI fast and responsive during heavy labeling tasks.
- Deployed RAG services with AWS Lambda + S3 + RDS; reduced inference cost/user ~22% and kept latency under 700 ms during peak time.
- Built CI/CD pipelines with automated testing and deployment using GitHub Actions and Docker, enabling fast, reliable releases with easy rollback across staging and production.
- Worked closely with ML engineers, data ops, and product leads to align infrastructure with evolving annotation workflows and model training cycles.
Feb 2016 - Dec 2019
3 years 11 monthsJunior Software Engineer
Synerise
- Junior full stack developer with hands-on experience building small web apps using React (Hooks, React Router), Node.js (Express).
- Worked with PostgreSQL and SQLite for databases and used socket.io to add real-time features like chat and notifications.
- On the frontend, focused on clean and responsive UIs using HTML5, CSS3, and basic Material UI components.
- Experienced working with version control using Git/GitHub, testing APIs with Postman, and collaborating through pull requests.
- Strong communicator with a growth mindset — asks the right questions, takes feedback well, and supports team collaboration in agile environments under senior developers.
Summary
Senior Full Stack Web Developer with 9+ years of experience delivering high-impact web and mobile platforms across healthcare, AI, and SaaS industries.
Specialized in React, Next.js, and Node.js with strong backend expertise in Python, FastAPI, and scalable infrastructure using AWS and Azure.
Proven success in building real-time systems, clean and testable APIs, and leading cross-functional teams with a focus on performance, CI/CD automation, and developer experience.
Languages
English
AdvancedPolish
IntermediateEducation
Oct 2012 - Feb 2016
Bialystok University of Technology
Bachelor’s degree · Białystok, Poland
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