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Frontend Developer in Amsterdam


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Job Description

Castor is looking for Javascript experts to bring our UI and UX to the next level!


Who are we?

We are the team behind Castor EDC (Electronic Data Capture), a web application that allows medical researchers to collect data for their clinical studies. We are one of the fastest growing HealthTech companies, having tripled our customer base in the last year. We are proud of the fact that our customers are our biggest growth engine. Once they use our product, they fall in love and tell their fellow researchers.


What is our goal?

To improve healthcare worldwide by enabling medical research through technology. We want to accelerate medical research by unlocking the potential of every researcher. We believe that the Castor products can become the global standard for medical data capture and management. To meet tomorrow’s healthcare challenges standardizing and reusing datasets is key. Starting with an easy to use and affordable EDC system, we help users in their entire research process. Using the large volumes of data and metadata collected in our systems, we want to provide researchers AI-driven services to make our core products smarter and smarter. This poses interesting challenges related to scalability, security, cryptography, AI and UX. We were recently awarded with a €1.1M EU Horizon 2020 grant that helps us to speed this along!


Who are we looking for?

To reach our goals, we are looking for experienced frontend developers that want to contribute to science while working in a challenging commercial environment. You have 3-5 years of experience with building up large-scale frontend javascript applications from scratch, preferably using React.


What will you be doing?

To keep our products at the frontier of innovation, your responsibilities will include:

  • Designing the architecture for our new React frontend application that will impact the daily life of thousands of researchers
  • Translating user requirements into beautiful new functionality with optimal UX
  • Migrate components from our ExtJS 3.4 and 6.5 projects to React
  • Collaborating with other engineers, product management and customer success representatives.
  • Investigating and building automated unit-, functional and acceptance tests
  • Teaching and mentoring other engineers about Javascript
  • Identifying opportunities for process and tool improvements and implementing them
  • Working on automated toolchains to build and integrate our applications

Our stack and tools
For the frontend of our applications we will build a new React-based frontend, where we currently use Sencha ExtJS 3.4 and 6.5. The backend consists of PHP7 applications using Zend Framework 2 and Doctrine 2, backed by multi-tenant MySQL/MariaDB databases.

Our toolset includes Slack, JIRA, Bitbucket, Confluence and Google for Business. We use Jenkins as a continuous integration server.


We offer

  • A job offer within a week (if we like you)
  • The chance to carve out your technical role in a fast-moving start-up
  • A way to help the world by improving medical research
  • The option to work from home 2 days a week
  • 30 vacation days per year
  • The opportunity to attend relevant tech conferences
  • A team of young, smart and driven colleagues
  • A spacious office with all amenities located in the south-east part of Amsterdam, next to Holendrecht Station
  • Free lunch, snacks and Friday afternoon drinks!
  • A great salary, bonuses based on company results and a pension plan



Essential skills

  • You have broad tech interests but specialise in Javascript (3-5 years experience), specifically with React.
  • You have designed and developed large (enterprise) applications
  • You have exprience with ExtJS, preferably with different versions of it, or are willing to learn its architecture
  • You have excellent problem solving and analytical skills.
  • You have strong verbal and written communication skills

Desired mindset

  • You prefer high quality, well-structured code over quick fixes and hacks
  • You educate yourself, read articles on new techniques, and keep up to date on the dynamic landscape of Javascript libaries and frameworks
  • You’re excited about the opportunity to help us scale from NL to EU to global, making sure all our customers have the best user experience
  • You relish the opportunity to help us with automated testing, security and Continuous Delivery
  • You have a strong customer focus


About Castor

  • Healthcare

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