Daniel “Klokie” Grossfeld

Senior full-stack engineer, architect and entrepreneur — Stockholm, Sweden.

27 years building for the web: complex data-driven products, e-commerce, media distribution, and regulated healthtech. Founding partner of four international companies, and a hands-on engineer throughout — I’ve led small, fast teams in New York, London, Paris, Barcelona and Stockholm, and I still write the code.

Lately, two things. I build with AI agents rather than just calling them — MCP servers, always-on agent infrastructure, versioned skills and workflows — and I introduced that way of working to an engineering team, where the lesson was that it only holds once the shared rules and documentation exist. And I build the interfaces that make large, structured data legible: a Visx graphing library for longitudinal medical data, and before that a layout engine that composed magazine pages automatically using computer vision.

Underneath both: TypeScript and Node, React and React Native, Python, event-driven services on Kafka and Postgres — plus the surrounding craft of making a platform survive its own history. I like owning a service end to end, and I like leaving a team faster than I found it.

Currently open to senior, lead and staff engineering roles — remote-first or genuinely flexible hybrid, southern Stockholm or fully remote. Get in touch.

Experience

Werlabs — Full-Stack Developer

Stockholm, 2024 → present (consultant, then employee from February 2025)

Health-tech platform for consumer blood testing, in a regulated Swedish environment.

Built and owned two production services end to end: an appointments and booking service integrating a third-party scheduling provider — entitlements, practitioner management, webhooks, Kafka events, booking and cancellation — which underpins the company’s paid video consultations; and a TypeScript/Playwright PDF-generation microservice that replaced a fragile legacy JVM stack, with service-to-service auth, browser isolation, monitoring and an autoscaling path.
Shipped the infrastructure around them: webhook consumers, health-check coverage, structured logging, feature toggles and proportional rollout.
Held continuity for the legacy platform through several departures — identity and user profile, results, the practitioner app — including a handover to an external partner.
Introduced AI-assisted development to the team (editor tooling, shared rules, reusable skills) and onboarded a new developer through review and context transfer.
Built a dynamic graphing library on Airbnb’s Visx that renders longitudinal medical data over time, used across consumer and B2B surfaces — large result sets, interactive time-series, and a component API other engineers build on.

Scania — Elain Advanced — Product Owner / Senior Back-end

Stockholm, 2023–2024 — data platform for a global truck manufacturer. Python serverless ingest APIs, SQL migration and modelling across GCP and AWS, owning both the backlog and the backend.

TV4 / Telia / C More — Senior Full-stack Developer

Stockholm, 2022–2023 — streaming and media distribution at national scale, across web and connected-TV clients. Editorial and content-delivery systems under real traffic, including PIN-code authentication and cross-domain consent handling.

Sneakersnstuff — Senior Full-stack / Tech Lead

Stockholm, 2020–2022 — led a small team building the React Native app (TypeScript, AWS, Swift for the native iOS layer) past a million monthly active users, multilingual and multinational across markets, languages and currencies. Migrated a large cross-platform codebase to TypeScript, integrated payment and logistics APIs, owned App Store and Play releases, and embedded a Unity game inside the app.

Enliven — Co-founder & CTO

Stockholm, 2017–2024 — AI-based media platform for professional creatives and premium personal brands. Raised 1 MSEK and built the whole stack myself — Node.js on MongoDB and MySQL with Docker, a REST API, a React front end — and the product itself: a design system that composed magazine-quality layouts dynamically using computer vision, years before the current AI boom.

My partner and I personally signed over 250 journalists, photographers, stylists and chefs from top-tier publications, who published on the platform from 2017 to 2022. When the consumer product stalled I productised the layout engine as a standalone API.

Odalisque Magazine — Co-founder & Technical Director

One of Sweden’s leading fashion, arts and culture publications, in print and on the web.

S2A Interactive — Founder

Independent studio building modern web architecture for SMEs across European and US media and fashion.

Surface to Air — Co-founder & CTO

New York / Paris, 2000–2008 — design studio serving publishing, music, film and fashion.

Earlier clients include MoMA, Tiffany & Co., Rawkus, Source, and New York Magazine. The longer list is on things I’ve worked on.

Building with agents

Two years of building with AI agents rather than just calling them:

Always-on agent infrastructure on a self-hosted Linux box — scheduled and event-driven jobs, messaging and mail gateways, and a migration between agent runtimes with the integrations kept intact.
MCP servers and tooling for my own data and task systems, plus multi-host repo and state management across three machines — repoman, written in Go.
Agent skills and workflows as reusable, versioned units. This is what I then introduced to the team at Werlabs, and the lesson was that adoption only holds once the shared rules and documentation exist — that is what makes agent output something a team will accept in review.

Research and side work

Promobilia / KTH — 2025 → present — assistive technology for deaf and hard-of-hearing users: real-time environmental sound recognition delivering haptic and visual feedback. Unity on iOS with an Apple Watch companion, on-device inference (YAMNet embeddings plus a trained classifier head, exported to ONNX), Core Haptics and a native WatchConnectivity plugin. Co-authored an ASSETS 2026 submission.

Kendra Foundation — London, 2009–2013 — two EU FP7 research projects. EU liaison for SARACEN, authoring proposals accepted by the European Commission; and P2P-Next — peer-to-peer content delivery and adaptive streaming, 21 partners — as a senior back-end engineer. Distributed machine learning on a Hadoop/Mahout cluster with Python.

This site — Astro, TypeScript and Cloudflare Workers: fully bilingual, with per-locale routing, translation fallback, canonical and hreflang policy, locale-aware structured data, edge delivery and a content pipeline that publishes from source on push. Where I try things before recommending them.

Stack

Core: TypeScript, Node.js, React, React Native, Python, Astro, Postgres, Kafka, REST and event-driven APIs, Playwright, Docker, CI/CD.

Cloud and delivery: AWS, GCP, Cloudflare Workers, CDN and edge delivery, observability and structured logging, feature flagging and progressive rollout.

AI and agents: LLM agent runtimes, MCP server design, agent skills and scheduling, retrieval over local corpora, computer vision, on-device inference (ONNX), distributed ML.

Mobile and realtime: React Native, Swift, Unity (C#), Core Haptics.

Also: Go, Keycloak and OIDC, i18n routing and content pipelines, data visualisation (Visx, D3).

Education

Boston University — cum laude, 1993–1998 B.S. Computer Systems Engineering · B.A. Music Theory and Composition

Languages

English (native), Swedish, Spanish, basic French.

Full history on LinkedIn · things I’ve worked on · get in touch