About
Product engineer, not just a developer
I’m Damien Mercier, a freelance product engineer based in France. I build and improve web products used by real people, mostly with React, Next.js and TypeScript, across the stack when the feature needs it.
The title matters to me. A developer is handed a ticket; a product engineer is handed a problem. I contributed to the development of Campus Coach, a SaaS platform for runners and coaches, and the work I’m proudest of there wasn’t the cleverest code. It was features where understanding what coaches actually needed changed what we built.
Why this job? Because software is the rare craft where you can go from “someone has this problem” to “someone is using the solution” in weeks, with your own hands, at every layer. I like the whole loop, from the product conversation to the architecture decision to the pixel detail, and freelancing lets me do the whole loop for teams that need it.
Method
How I work
01
Understand
Before writing code: what problem are we solving, for whom, and how will we know it worked? Half the value of a good engineer is the questions asked here.
02
Design
Shaping the solution: the user experience and the technical approach together, because they constrain each other. Small, reviewable decisions over big-bang plans.
03
Build
Clean, typed, tested code that fits the codebase it lives in. I optimise for the next person who reads it. Often future you, sometimes future me.
04
Ship
A feature has no value in a branch. I take work all the way to production, and I care about what happens when real users touch it.
05
Improve
Shipping is the beginning. I watch how features behave in the real world (performance, bugs, usage) and improve them based on evidence.
Toolbox
Technologies I use
Tools are a means, not the point, but these are the ones I reach for. See how they translate into services and real work.
React · TypeScript · Next.js · Tailwind CSS · TanStack Query · Zod · Vite · Node.js · REST APIs · Postgres · Supabase · SQL · Anthropic API · n8n · Vitest · Cypress · Figma · Sentry · Three.js / React Three Fiber
Have a product to build or improve? Let’s talk.
Tell me about your product and where it needs to go. I usually reply within one or two business days.