Location: Delft (Hybrid, min. 2 days/week) | Type: Part-time/Full-time (24-40 hours) | Start: 1 November 2025

At Praxa Sense, we’re redefining non-invasive health monitoring with our optical innovation ALIS – a speckle-based biosensor enabling new frontiers in remote vital sign tracking. 

We’re looking for a Senior Web Developer to own the application layer that connects our breakthrough hardware to its users. You’ll craft an Electron-based web app that ingests real-time biosensor data, processes it in JavaScript/TypeScript, and turns it into interfaces that are both beautiful and functional – from engineering dashboards to polished evaluation tools for high-profile customers. 

Your work won’t just be “screens and buttons” – you’ll be shaping how the world experiences our sensor. When a global tech company tests ALIS in their product lab, your interface will be their first impression. 

What you will do:

  • Design and develop the entire front-end experience for our Electron-packaged web application – from rapid prototypes to production-ready tools. 
  • Build real-time visualization components using graphing and charting libraries of your choice (e.g., D3.js, Plotly, Recharts) for live biosignal monitoring. 
  • Implement responsive, accessible UI patterns in React that adapt to both internal engineering workflows and customer evaluation use cases. 
  • Integrate directly with hardware using Web Serial, WebSocket for efficient data transport. 
  • Collaborate with firmware and Python engineers – understanding enough C++ to discuss low-level changes and occasionally contributing Python glue code. 
  • Tailor the UI/UX for prospective customers during integration trials – ensuring they can easily explore, understand, and export sensor data. 
  • Take architectural ownership: propose libraries, set coding standards, and maintain performance in data-heavy scenarios – in alignment with the broader team. 

What we are looking for:

  • 5+ years building performant, real-time, or data-heavy applications. 
  • Expert in JavaScript/TypeScript with deep React knowledge (bonus: experience with Electron and data visualization libraries). 
  • Strong front-end design sensibilities – able to make complex data feel intuitive and engaging. 
  • Comfortable integrating with hardware APIs, handling streamed/binary data, and bridging systems via protobuf or similar serialization formats. 
  • Some familiarity with C++ and Python to ease cross-team collaboration. 
  • Thrives in lean, agile environments – enjoys wearing multiple hats and taking ownership. 
  • Believes in synergy: great products emerge when experts in different domains collaborate closely. 

What we offer:

  • Salary €5.000–€6.500 per month, plus the possibility of a share/equity component. 
  • A high-impact role with full ownership of the web application in a deep-tech product. 
  • Direct collaboration with a senior firmware/Python developer and a hardware/firmware engineer – your work is the bridge between them and our customers. 
  • The chance to shape how world-leading companies evaluate and integrate our technology. 
  • Hybrid work culture: in-person collaboration in Delft at least 2 days/week. 
  • The satisfaction of building technology that directly improves health monitoring. 

Please also consider to apply if you do not fit all of the above mentioned criteria. We are actively hiring for inclusion and diversity.

Send us an email via: hr@praxasense.com with a motivation letter and your CV.