Senior Fullstack Engineer (m/f/d) - AI Health tech

voize; Berlin; Hybrid; EUR 70,000 - 120,000; Part time

Benefits offered by this job

30 vacation days

Germany Transport Ticket

Urban Sports Club

Blinkist/Audible access

Language courses

Job summary

voize is building AI companions to streamline workflows for frontline workers. We are seeking a Senior Fullstack Engineer - Freelance to co‑own the ML App, the in‑house platform for annotation, data exploration, ML training orchestration, model evaluation, and HIPAA‑compliant data flows from customer to model.

You will work on React/TS SPA, Kotlin services, and ETL on EKS, ship features for labeling, data exploration, and ML tooling, maintain CI/CD, and collaborate with Platform team on

Qualifications

• 5+ years building production fullstack web apps with React + TypeScript.
• Excellent Kotlin (or JVM) backend experience - services, ETL/data pipelines.
• Demonstrated ownership of a complex, production‑critical system.
• Comfortable engineering with regulated / sensitive data (HIPAA, GDPR, BAA, PHI, or similar).
• Strong product / UX instincts (annotation, labeling, data exploration, ops UI)

Responsibilities

• Co-own the ML App codebase (React/TS SPA + Kotlin services + Kotlin ETL on EKS).
• Design and ship features for data labelling, data exploration, ML training orchestration, model evaluation.
• Drive the next iteration of in-house annotation tooling - UX, throughput, task-type extensibility.
• Maintain CI/CD, EKS deploys, and LGTM‑stack observability for ML App; triage and fix defects.
• Pair with the Platform team on platform‑side prerequisites (FGA proxy, OIDC) that the new training flows depend on

Skills

React+TS

Kotlin backend

Ownership

HIPAA/GDPR

Product/UX

Job description

Why voize? Because we’re more than just a job!

At voize, we believe the greatest gift to frontline workers is time - time to care, connect, and be present. Today, that time is lost to busywork and complex systems that pull them away from what matters most: people.

Our vision is to change that by building AI companions that seamlessly take over digital workflows. We don’t replace humans with technology - we amplify their impact.

Our mission is backed with a $50M Series A funding led by Balderton Capital, with support from HV Capital, Y Combinator and other leading VCs. Today, 2,000+ facilities trust voize, and over 200,000 users rely on our AI companion to ease their daily workload.

As a dynamic team, we combine first-in-class technology with meaningful social impact. And now, we’re looking for you to join us on this mission!

Your Mission

As a Senior Fullstack Engineer - Freelance at voize, you will be a co-owner of voize’s ML App - the in-house platform for annotation, data exploration, ML training orchestration, model evaluation, and the HIPAA-bearing data flows that move PHI from customer to model. Make in-house tooling good enough that revisiting Labelbox/Encord-style vendors is permanently off the table, and unblock HIPAA‑compliant training on US customer data.

Your Daily Business - No two days are alike

• Co-own the ML App codebase (React/TS SPA + Kotlin services + Kotlin ETL on EKS)
• Design and ship features for data labelling, data exploration, ML training orchestration, model evaluation, model playgrounds, and ML‑issue triage
• Drive the next iteration of in-house annotation tooling - UX, throughput, task-type extensibility - to the bar where vendor revisits are unnecessary
• Maintain CI/CD, EKS deploys, and LGTM‑stack observability for ML App; triage and fix defects
• Pair with the Platform team on platform‑side prerequisites (FGA proxy, OIDC) that the new training flows depend on

Your Skillset - What you bring to the table

• 5+ years building production fullstack web apps with React + TypeScript
• Excellent Kotlin (or JVM) backend experience - services, ETL/data pipelines, schema design
• Demonstrated ownership of a complex, production‑critical system
• Comfortable engineering with regulated / sensitive data (HIPAA, GDPR, BAA, PHI, or similar)
• Strong product / UX instincts (annotation, labeling, data exploration, ops UI)

Growing together - what you can expect at voize

• We are a fast‑growing startup, that means you will tackle challenges, grow quickly, and make a real impact, giving frontline workers more time for people
• We foster an open, collaborative culture with regular team events, whether you work from our Berlin office or remotely across Germany
• Become a co‑creator of our success with stock options
• Generous perks: 30 vacation days plus your birthday off, Germany Transport Ticket, Urban Sports Club, regular company off‑sites, and access to learning platforms such as Blinkist and Audible, plus free language courses
• You decide when you work best, that means flexible working hours and a good hybrid set‑up.