Fractional CTO · AI & Data

Building the Future of Software Every Loop Closed

Fractal Loop is Kilian Marjew, an Amsterdam-based fractional CTO. I turn AI and data plans into working software.

Start a Conversation View Work
20+years shipping 4×CTO / Head of Engineering
Selected Work

Recent Work, Closed Loops

Technical Lead · Smart Home

Four Codebases, One Spec, Ten Agents

Technical lead for the whole software side of a connected smart-home device: firmware, cloud, app and the protocol spec that binds them. Up to about ten AI agents build in parallel, every change goes through a merge train, and overnight runs test on real hardware. Every decision that matters is mine.

ESP-IDFMQTTFlutterClaude Code
specfirmwarecloudappmerge traindevicephoneovernight tests ✓
Fractional CTO · Fintech

Answers That Cite Their Source

append-only · every entry keeps its source↳ human review AI answercited ✓

Data and AI strategy, proven in weeks with a working core: every figure keeps its source, and the AI adviser cites its evidence or abstains.

Method

Flow Items: Running AI Agents Across Repos

Every handoff a small written brief in git, every status change a commit. Across my engagements, about 460 items in nine weeks.

Side Project

Loop Smith

three days · no road twice ✓

A personal app for planning multi-day motorcycle trips, shaped by riding its own routes.

Experience

Twenty Years, Woven into Every Loop

2004 · 2013

Core Developer → Tech Lead

Hyves

Nine years at the Netherlands' largest social network. Designed and built the REST API, led the games platform, and owned the identity service. Scale, the hard way.

REST APImassive scale
2004 · 2018

Developer → CTO

Tiqets · HidashHi · Effacts

CTO at a WebRTC video SaaS, backend at a global ticketing marketplace (prediction models, caching), and the full-stack groundwork across many stacks.

WebRTCML / prediction
2018 · 2020

Senior Backend & Blockchain

Blockport (acquired by BUX)

Core engineer on a social crypto exchange: microservices for auth, payments, deposits and compliance, plus Ethereum smart contract integrations.

microservicessmart contracts
2020 · 2021

CTO

Circularise

Hands-on CTO for supply-chain traceability on blockchain. From pilot with one developer to a stable product and a team of five-plus, with Zero Knowledge Proof research demos.

ZKPMVP to product
2021 · 2025

Head of Engineering

The Inner Circle

Management team at a dating platform where a date is planned every 6 seconds. Grew the team, set the tech strategy, and turned it into a true scale-up.

scale-uptech strategy
2025 · now

Fractional CTO

Fractal Loop

Everything above, in one practice: strategy that gets proven with working software, built AI-native, with every decision that matters made by a human.

AI-nativefractional CTO
Services

Where I Come In

Fractional CTO

Technology leadership without the full-time hire: tech vision, team, engineering culture, and the calls nobody else in the room can make.

strategyteam

AI & Data Foundations

A data core you can trust, and AI on top that cites its evidence or abstains. Roadmaps with measurable gates instead of dates.

data strategyAI strategy

AI-Native Delivery

Spec-first teams where AI agents do most of the building, in parallel, and humans review and decide. I set it up and teach your team to run it.

agentsspecs

Architecture for Scale

Event-driven and domain-driven systems that grow with you. Legacy replaced piece by piece, not in one risky big bang.

microservicescloud

Hardware to App

Firmware, cloud, app and the protocol between them, run as one product, with tests on real hardware.

IoTOTA

Advisory & Mentoring

A sparring partner for engineering leaders working through growth, technical debt or a move to AI-first ways of working.

coachingprocess

Tools I work with

the whole stack, from silicon to AI
  1. AI
    • Claude Code
    • agentic development
    • MCP
    • RAG
    • LLMs
  2. Apps & hardware
    • Flutter
    • ESP-IDF
    • WebRTC
  3. Data
    • PostgreSQL
    • Kafka
    • Redis
    • MQTT
  4. Cloud & infra
    • AWS
    • GCP
    • Kubernetes
    • Terraform
    • Docker
    • CI/CD
  5. Languagesacross every layer
    • Python
    • Go
    • TypeScript
    • C
    • PHP
    • Solidity
Get in Touch

What's Your Loop?

Building something where AI and data have to hold up in production? Send me a line. I'll tell you straight whether I'm the right person for it.

Emailkilian@fractalloop.dev LinkedInConnect with me
Let's talk →

kilian@fractalloop.dev