Full-stack developer · Amsterdam

Jonas Gundlach

I design and build websites and web apps for founders, small businesses and studios, from the first sketch to the day it goes live. Clear scope, a fixed price, and a date you can plan around.

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Things I've built

Weeztix

Mar 2023 – now

Sole developer of the marketing site and CMS for three years. 400 pages, six languages, two million visits a year.

cms
component library
animation
seo

StrategyOS

Jan 2026 – now

An AI-powered strategy platform. Lead developer on the research and analysis modules.

llm analysis
data enrichment
scraping
rest api
auth

myRoomies

May 2026 – now

A Dutch room-rental marketplace, built from scratch: marketing site, app, payments, the lot.

ranking algorithm
payments
live chat
database
ads

bydynamics + projectstack

Jun – Sept 2026

Two corporate sites with block-based content the client edits themselves.

cms
email automation
analytics
hosting

Ticketing Index

Mar – Jul 2026

A multilingual self-assessment tool that scores event organisers and turns the result into a shareable report.

assessment
workflow automation
i18n
database

PayperChain

Jun 2025 – May 2026

Refactored the payment dashboard for a blockchain-based pay-per-use platform.

blockchain
openapi
kubernetes
docker

Miami Nice

2022 – 2024

Festival site for a student festival in Eindhoven, with a ticket shop that reads live from the ticketing API.

ticket shop
api
video
forms

What I can build for you

Custom website

Marketing site, landing pages, portfolio

Design and build from scratch, with a CMS so you edit it yourself, forms, analytics and the SEO basics. You own everything.

from €2,500

about two weeks

Web app

Accounts, data, payments, dashboards

The product behind the site: auth, database, payments, admin tools. Built to be maintained, delivered with documentation and a handover.

from €5,000

four to eight weeks

Custom

Something that doesn't fit the other two

Integrations, internal tools, a rebuild of something that exists, or an extra developer on your project. Tell me what you need and I'll quote it.

on request

depends on scope

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About

I'm Jonas, a developer from Amsterdam with three years of shipping production sites and apps. I'm always excited to hear what founders are working on, and to help them get the first version out the door. I also love my two cats, Lilli and Baloe.

Have something to build?

Send me your idea. I reply within a day.

Start a project