Daniel “Klokie” Grossfeld
Senior Full-Stack Engineer / Architect — Stockholm
25+ years · Medtech · Sustainability · Media · E-commerce
Profile
Product-minded senior engineer with 25+ years building data-heavy, user-facing platforms in regulated and high-traffic environments. Strong in TypeScript, React, Python, AWS, Docker, Kafka, PostgreSQL, and TDD. Extensive experience integrating AI/LLM systems (OpenAI, Claude, Gemini) using RAG and feedback loops (RLHF-style workflows). Founder, product owner, and end-to-end system owner.
Tech Stack (Primary)
- TypeScript
- React / React Native
- AWS (Lambda, ECS, Fargate, S3, SQS)
- PostgreSQL
- Docker, Kafka
- Python (FastAPI, SQLAlchemy)
- Pandas, NumPy
- CI/CD, TDD
- Swagger / OpenAPI
AI / ML / LLMs: OpenAI, Claude, Gemini · RAG (vector search, embeddings) · prompt pipelines · evaluation & feedback loops (RLHF-style)
APIs: REST, GraphQL, OpenAI, OAuth, Contentful, Iterable, Google APIs, Unity, auth & payment services
Experience (Selected)
Werlabs AB (Medtech)
— Senior Full-Stack Developer
2024 – Present
Built and owned core patient-facing and clinical systems in a regulated medtech environment.
Designed and shipped:
- High-volume PDF generator for medical journals
- Appointments booking service
- Major parts of the customer health journal
Stack: TypeScript, React, Docker on AWS, Kafka, PostgreSQL, strict TDD.
Strong focus on data correctness, reliability, and developer velocity.
Scania Group / Elain (Sustainability)
— Senior Full-Stack Developer & Product Owner
2023 – 2024
Worked in a small elite team with full ownership of product and platform.
Built cloud-native APIs using:
- AWS (Lambda, ECS, Fargate, S3, SQS)
- Python (FastAPI, SQLAlchemy)
- PostgreSQL
- Swagger/OpenAPI
- Pandas & NumPy pipelines
Elain: emissions intelligence platform enabling high-precision CO₂ calculation, traceability, and regulatory compliance.
Later acquired by LOTS Group to scale data-driven emissions reduction globally.
SNS (Sneakersnstuff)
— Senior Full-Stack Engineer
2020 – 2022
Led development of React Native app for 1M+ users.
Migrated large codebase to TypeScript, built CI/CD (Bitrise), and integrated Contentful, Iterable, Sentry, Unity, and commerce/auth APIs.
TV4 / Telia
— Senior Full-Stack Developer
2022 – 2023
Worked on high-traffic streaming platforms (millions of users).
Built shared React + TypeScript codebases, merged backend services, and integrated chatbot systems.
Enliven
— Co-founder & CTO
2016 – 2024
Built AI-based media platform for creators and premium brands to design, distribute, and monetize content.
Owned architecture, data model, and platform direction.
S2A Interactive
— Founder & System Architect
2007 – Present
Designed and built modern web platforms for:
Absolut Vodka, New York Magazine, Toyota, Atlas Copco, SXSW.
Education
Boston University — BSc Computer Systems Engineering + BA Music Theory & Composition