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Freelance · Paris & Remote

Koa
Dev Freelance Fullstack Developer & Tech Lead in Paris

Senior Fullstack Developer & Tech Lead with 15+ years of experience in startups. Cloud architectures, distributed systems, AI & high-traffic applications — I turn your complex ideas into scalable products.

TypeScript
React
Node.js
AWS Lambda
Cloud Architecture
Serverless
PostgreSQL
Kubernetes
GCP
GraphQL
CI/CD
Tech Lead
AI / LLM
TypeScript
React
Node.js
AWS Lambda
Cloud Architecture
Serverless
PostgreSQL
Kubernetes
GCP
GraphQL
CI/CD
Tech Lead
AI / LLM

What I can
do for you

Cloud Architecture & Serverless

Designing highly scalable event-driven architectures on AWS and GCP. Lambda, SQS/SNS, Kubernetes — systems built to handle the load.

  • AWS Lambda
  • SNS / SQS
  • GCP
  • Kubernetes

Fullstack Development

End-to-end TypeScript web applications, from React frontend to Node.js backend, with a strong focus on quality and maintainability.

  • TypeScript
  • React
  • Node.js
  • PostgreSQL

SaaS & Complex Products

From idea to production: multi-tenant SaaS products, third-party API integrations, payment systems, CI/CD pipelines.

  • SaaS
  • Stripe
  • OpenAI
  • CI/CD

AI & Automation

LLM integration (OpenAI, Claude, Mistral), RAG, autonomous agents and AI workflows. From proof of concept to large-scale production.

  • LLM
  • RAG
  • AI Agents
  • OpenAI

Tech Lead & CTO

Technical team leadership, code standards definition, code reviews, and mentoring. I take ownership of your project's technical vision.

  • Management
  • Architecture
  • Code review

Technical Audit & Consulting

Code and architecture audits, bottleneck identification, actionable recommendations. I notably conducted the technical audit of a startup as part of its acquisition.

  • Audit
  • Performance
  • Consulting

Cloud Architecture & Serverless

Fullstack Development

SaaS & Complex Products

AI & Automation

Tech Lead & CTO

Technical Audit & Consulting

Matthieu Guigon
15+ years building products that last

Matthieu Guigon
Matthieu Guigon — Fondateur de koa-dev

Trained at École 42, I started in Parisian startups before heading to Silicon Valley — an internship won through a hackathon at Milestone Project in San Francisco.

Since then, I've grown from developer to Tech Lead, including a stint as interim CTO at PathMotion during its acquisition.

Freelance since March 2023, I'm also CTO of Flashpricer, an AI-powered e-commerce repricing SaaS platform that I architected and built from scratch.

I love complex problems, architectures that withstand scale, and teams that ship.

Based in Paris, I work in French and English, remotely or on-site depending on your needs.

Estimate your
project budget

Mission type
Estimated duration
Engagement
Rate estimate
700820
per day (excl. VAT)

Indicative estimate based on mission type, duration and engagement. The final rate is adjusted after discussing your project.

Refine with me

Let's talk about your next project

Have an ambitious project, an architecture to rethink, or need an experienced tech lead? I'm available for new freelance missions.

The tools
in my arsenal

Frontend

Backend

Cloud & Infra

Data & AI

Frequently asked questions

I work on fullstack development, cloud architecture, tech lead / CTO roles and AI integration. From short-term support over a few weeks to long-term technical leadership spanning several months.

TypeScript, React, Next.js, Node.js on the application side. AWS (Lambda, SQS, DynamoDB), Terraform and Docker for infrastructure. OpenAI, Claude and Mistral for AI projects.

Both, depending on the context. For long-term engagements, I prefer a daily rate model. For well-scoped projects (audit, MVP, migration), fixed-price is often more suitable.

I handle 1 to 2 projects in parallel. Reach out to check my current availability — I respond within 24 hours.

Yes, it's one of my most common engagement formats. I take ownership of the technical vision, hiring, architecture and dev team management.