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AmsterdamApp & Custom Software Development in Amsterdam

Software development for Amsterdam. We build high-performance mobile apps and web platforms for the Netherlands' thriving fintech and martech ecosystems.

App369 is a founder-led software studio based in Miami, Florida. Simon builds custom mobile apps, web platforms and AI features for businesses in Amsterdam and beyond, working remotely on Eastern Time.

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A phone standing on a dark grid floor showing a simple map with a light blue location pin
Fiverr
5.0 · 127 reviews
Own product
Workspace369
Fixed-price offers from
$450

Same fixed prices wherever you are

Fixed scope, fixed price, paid upfront. The work happens in writing; no call needed.

FL
Based in Miami, Florida
ET
Eastern Time working hours
Fixed
Price in writing before work starts
1
Codebase for iOS, Android and web

Why App369

Why Amsterdam Businesses Choose App369

What Amsterdam teams should know before working with App369.

Serving Amsterdam, Rotterdam, The Hague, Utrecht, and the Randstad region

Focus on fintech and martech

Focus on Dutch regulatory frameworks including AFM compliance and PSD2

What Simon builds

Software Development Services in Amsterdam

From the Zuidas financial district to Amsterdam Science Park, we deliver software that powers the Netherlands' most ambitious digital ventures.

Mobile Apps

iOS and Android apps built with Flutter from one codebase, from concept to App Store launch.

  • iOS & Android
  • Cross-Platform
  • App Store Optimization
  • Maintenance & Updates
from $9k

Web Development

Fast websites and web applications, built for search and for phones first.

  • Custom Design
  • E-Commerce
  • SaaS Applications
  • SEO Optimization
from $6k

Custom Software

Internal tools, integrations and back-office systems engineered around how your team already works.

  • Enterprise Development
  • API Integration
  • Cloud Migration
  • Technical Consulting
from $1.2k

How it works

The 4-Phase Development Process

A written scope and four clear phases keep Amsterdam projects predictable.

  1. Discovery

    Understanding your vision, goals, and market requirements through stakeholder interviews and competitive analysis.

  2. Design

    Creating clear UI/UX with interactive prototypes you can click through before the build starts.

  3. Development

    Building with Flutter, Vue.js, Node.js, and GCP using 2-week Agile sprints with weekly milestone reviews.

  4. Launch

    Deployment to production with crash and uptime monitoring and ongoing maintenance.

Technologies

  • Flutter
  • TypeScript
  • Node.js
  • GCP
  • Firebase
  • Vue
  • JavaScript
  • Python

Questions

Frequently Asked Questions

How long does a typical project take?

It depends on scope. As a rough guide, a marketing website takes 4-8 weeks, a web application 2-4 months, and a mobile app 3-6 months. Every Amsterdam project starts with a written scope and milestone plan, so you know the timeline before any build work starts.

Do you provide ongoing support?

Yes. After launch App369 offers maintenance that covers bug fixes, iOS and Android OS updates, security patches, dependency upgrades and small feature work, so your Amsterdam app keeps working as the platforms change.

What's your pricing model?

Fixed-price offers are paid in full before work starts, at the prices published on the fixed-price page. Larger builds start with a paid scoping and are then quoted in writing, with their payment schedule, and start only with your yes.

Can you work with existing projects?

Yes. Simon takes over existing codebases, especially Flutter and Firebase apps, for code audits, bug fixes, new features and migrations. Amsterdam businesses with an app that stalled or a developer who left can start with an audit before committing to a larger build.

What technology do you use?

Mostly Flutter for iOS, Android and web apps from one codebase, Firebase and Google Cloud for backends, and Vue/Nuxt for websites. For AI features Simon integrates large language models for assistants, document extraction and automation.

Simon Dziak - Founder of App369

Your Development Partner

Simon Dziak

As founder of App369, I personally oversee every project App369 takes on, from scoping to launch. I build with Flutter, Firebase and Google Cloud, and I also built and run Workspace369, a client-management platform for freelancers and small businesses. Based in Miami, Florida, I serve clients across Amsterdam and nationwide.

Start Your Amsterdam Project

Get in Touch View Pricing

Fiverr reviews / 95 on app work

What buyers said about working with Simon

Read 126 of the 127 reviews
  • “Szymon was able to answer all the questions I had about this project. It was great to walk through all the details with him.”
    Rebecca, United States, August 2021. Custom order on Fiverr
  • “The finest person I've ever had to educate me and aid me with my app's launch. When it comes to assisting, he is very friendly, educated, and patient. I would suggest this individual for any job! It surpassed all of my expectations! If I had the option, I would have given more stars. Choose Szymon to help you instead of looking anyplace else; you will not be disappointed. Szymon thank you for all the help!!!”
    Dustin, United States, July 2021. Custom order on Fiverr
  • “Excellent client service!!! We talked through messaging and placed a modest order to speak on the phone to discuss more detailed details. I'm looking forward to finishing the project's final stages. It comes highly recommended!”
    Dustin, United States, July 2021. Custom order on Fiverr

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