Curriculum Vitae – Sander Hahn

Freelance Developer

Personal Information




Master's Degree Computer Science at Vrije Universiteit Amsterdam

Studied computer science and technical practical development assignments included:



Experienced developer that can easily adopt to new projects. Enjoy researching new languages, libraries and frameworks to find out how they can provide business value.


Developer at Charper Bonaroo

May 2021-Now, Haarlem

Developed Joget plugins that help to enable digital competition forms for KNHB in Java. Helped developing an Elixir/Phoenix application for chip registration of dogs. Helping with issues on Node/NestJS based website.


May 2019-May 2021

Took some time off and experimented/learned different languages such as the Rust system programming language. One project was cancelled because of the corona scare. Father was ill and temporary took care of my parents at home.

Python/ServiceNow Developer at Divider/KPN

Mar 2018-Mar 2019, Leiden

Developing ServiceNow workflow integration of business processes using webservices in Python. SD-WAN configuration for multisite networks and provisioning using api integration (UniFi/FortiNet).

Elixir/Phoenix Developer at DPG Media

Oct 2017-Feb 2018, Amsterdam

Part of the team to built a greenfield video as a service platform that integrates with the MyChannels video management system written in Rails. The platform enables separate labels from De Persgroep and other websites to integrate videos, channels and series into their existing websites. The integration uses server-to-server communication to enable the system to be continuously developed by a centralized team.

Rails Developer at Schoolfoto

Dec 2016-Oct 2017, Noordwijkerhout

Rails developer on the webshop and backend for photo products. We improved user friendliness and reliability by merging the webshop/authentication/order subsystems. The product catalogue is remodelled using a self-referential hierarchical model. The photo selection widget is rewritten using VueJS.

Rails/Cordova Developer at Zisoo

Nov 2016-Apr 2017, Schiphol-Rijk

Developer of a Rails backend and a Cordova mobile app using VueJS Framework7 for an educational app that enables trainers to quiz students over time and track their knowledge of the course material. The backend uses pundit for authorization and is built to support multitenancy. The mobile app uses ActionCable/websockets for real-time team chat and scheduled questions using Firebase push notifications.

Elixir/Phoenix Developer at Charper Bonaroo

Jul 2016-Oct 2016, Almere

Elixir/Phoenix developer on prototypes for administering team composition/dynamic signup forms and integration with existing national score systems that track competition results.

Rails Developer at Impraise

May 2016-Jun 2016, Amsterdam

Developer of an extra authentication feature based on SAML to enable large enterprises to reuse already present authentication systems to log into the Impraise application.

Rails Developer at YoungCapital

Oct 2015-Feb 2016, Hoofddorp

Rails developer on multiple Rails applications that drive YoungCapital as an employment agency. The development involved a dashboard based upon React, candidate search using ElasticSearch, image reprocessing on S3, video resumes and sharing credentials using jwt.

Freelance Developer at Hackers & Founders Amsterdam

Nov 2013-Dec 2015, Amsterdam

Developing a platform that manages appointments using Rails and PostgreSQL/PostGIS and sends mails on event triggers. Ansible based provisioning of Ubuntu servers for hosting Rails and PHP applications. Parttime development on a single page application that manages marketing champagnes for retailers using AngularJS that integrates with a restful api. Dynamic aggregate charts are generated using Highcharts and ElasticSearch. Development of a questionnaire system in AngularJS and the use of Swagger as an API specification between the frontend and backend system.

Rails Developer at WRTS

Sept 2015-Oct 2015, Hoofddorp

Rails/BackboneJS developer on a educational application with a very large database that enables students to practice word translations.

Rails Developer at Cowlinq

Jul 2015-Sept 2015, Hoofddorp

Rails developer on a custom CRM integrated in the backend of a marketplace application that enables sales to track progress the onboarding of new customers.

Golang/ElasticSearch Developer at HotelSpecials

May 2015-May 2015, Remote

Developer of website tracking scripts for Google Tag Manager that sends visitor information to a backend written in Go and stores it into ElasticSearch. The data can be analysed/visualized using Kibana.

Rails Developer at Medid

Apr 2013-Aug 2013, Hilversum

Developer of a lead generation module inside a modular Rails CMS that works using geographical distance using PostGIS. Legacy CMS and CRM systems content is imported in the new application. The newsletter module is extended to handle merge fields.

Rails Developer at Springest

Sept 2012-Feb 2013, Amsterdam

Rewrite of a CakePHP administrative backend into Rails. The migration consolidated all code to Rails and enables easier continued development. The backend is a multitenant system where each publisher can only see and edit their own published content.

Android/Rails Developer at Moop Mobility

Jun 2011-Jul 2012, Amsterdam

Android developer of additional functionality into an existing self-service application for employees of a large cleaning company. Developer of a Rails backend for a checklist app running on iPads that synchronises and produces email and pdf reports. The application is used to monitor conditions to prevent infections in hospitals.

Developer at Divider

Oct 2009-Feb 2011, Leiden

Developer of a dashboard that measures performance of services that are offered to decentralised customers. Automatic extraction of snmp information such as: line throughput, assigned ip addresses of hardware inside the network and provisioning of devices and authentication systems. The dashboard makes it possible to administer and manage a large number of customers and systems from a single point of control.

Java Developer at Greetz

Jul 2007-Dec 2008, Hoofddorp

Backend developer for a Spring Framework/Hibernate based application that is the backend for a Flash based card designer.

Developer at VU medisch centrum

Sept 2000-Jun 2007, Amsterdam

Parttime developer on intranet web applications for employees of the hospital. The reports are built upon calculations on data extracted and aggregated from PeopleSoft.

Java Developer at Divider

Feb 2005-Feb 2006, Leiden

Helped develop a Swing based internet application that is used for clients of an accountancy firm. The backend used XML messaging to integrate data with AccountView (software for business administration).

Internship at COSS

Mar 2005-Sept 2005, Hilversum

Research project to evaluate Microsoft .NET integration in combination with Micro Focus COBOL to enable rich user interfaces on legacy applications.