Custom Websites
Performance-first websites built to reflect the real quality of the business behind them.
bespoke design and frontend buildCMS for in-house content managementSEO foundation and optimisation
Bespoke web development · Paris, France
Web development, crafted with precision.
Custom websites, web applications, and digital products for businesses that expect the same level of craft in their code as in the rest of their brand.
Clean, maintainable code built to last well beyond launch
Architecture decided before a single line is written
Transparent scope and fixed-price delivery, always in euros
From a single landing page to a full-stack platform
30+projects delivered
6countries served
10 daysaverage project completion
98+%on-time delivery rate
100%mobile-responsive delivery
95+average PageSpeed score
100K+monthly visitors across client sites
gessli-dev — project overview
Performance
A+
Delivery
On time
Project readiness
Precision-builttested · documented · delivered
Who we work with
Startups, growing businesses, and established companies that need web development done right.
We work with businesses at every stage — from a founding team validating an idea to an established company whose current platform has hit its limits.
Early-stage startups
MVP and product validation. Built quickly, built correctly, with architecture that survives when you need to scale.
Growing businesses
Your current site or application is holding you back. We rebuild it properly, without months of disruption.
E-commerce brands
Custom stores built beyond what templates allow — designed around how your business actually operates.
Service companies
A digital presence that communicates value clearly and brings in the right kind of enquiry.
What we build
Full-stack development — frontend, backend, and everything that connects them.
Every project is built in-house. No outsourcing, no template shortcuts where custom work is genuinely needed.
Web Applications
Full-stack applications with authentication, databases, and dashboards that run a real business.
React / Next.js frontendNode.js backenddatabase and API architecture
E-Commerce
Custom-built or Shopify-based stores with checkout flows and integrations that work at scale.
Shopify custom themes and appsheadless commerce buildspayment and ERP integrations
API & Backend
Clean REST or GraphQL APIs and backend services that other systems can rely on.
REST and GraphQL API designthird-party integrationsbackground jobs and services
Selected work
A sample of what we have shipped.
Client names are withheld under NDA, but the outcomes are real. Full detail on each is available on a call.
+140% conversionE-Commerce · Replatform
Legacy store rebuild, homeware retailer
Four-step checkout cut to one, mobile conversion nearly doubled within a month of launch.
11 days to productionWeb Application
Booking tool, logistics operator
Replaced five dispatch spreadsheets with one scheduling app. Double-bookings dropped to zero.
98 PageSpeed, mobileCustom Website · Booking
Marketing & booking site, boutique travel agency
Rebuilt from a six-second mobile load time to a live-availability booking flow under a second.
How we work
No black boxes. You know what is being built and why, at every stage.
Web projects fail when requirements are vague, timelines are guessed, and communication disappears mid-build. We remove all three from the start.
Technical discovery
Requirements mapped precisely before writing a line of code. Scope, architecture, and constraints documented and agreed before development starts.
Design and prototype
Interface design with real content, reviewed and approved before build — because changes are cheap in Figma and expensive in production.
Development in sprints
Incremental delivery. Working software at the end of each sprint, not a distant reveal.
QA, launch, and support
Full cross-browser and device testing, performance checks, and a structured, documented handover.
What clients say
Client feedback will appear here as projects are completed.
“I sent over a messy Figma file and a rough idea of what I wanted, and somehow got back exactly what I had in my head, just cleaner. He asked good questions early instead of guessing.”
Élodie Marchand · Founder · France
“Communication was in English, which isn't either of our first languages, and it still went more smoothly than projects I've run with local agencies. Replies came within a day.”
Tomasz Wójcik · Product Manager · Poland
“Straightforward pricing from day one, no scope creep, and the site has been running for eight months without a single issue on our end. Exactly what was promised.”
Camille Rousseau · Founder · France