(Freelance) Senior Backend Engineer (m/f/d) - Agent SDK
voize · Remote · Berlin · Birmingham · Bucharest, Romania · Rosenheim · Paris · Dortmund · Göttingen · Hannover · Karlsruhe · Munich · Warsaw, Poland · Cologne · London · Krakow, Poland · Hamburg · Bremen · Nuremberg ·
COMPENSATION
€•• – ••k
Listed on the employer's job board (Ashby)
- Senior Backend Engineer
- Kotlin + JVM
- Agent SDK focus
- Hybrid (Germany)
- Stock options
Join voize as a Senior Backend Engineer to own the Agent SDK, the Kotlin foundation powering AI companions for frontline workers. You will shape the runtime, define client-facing contracts, and ensure that adding new agents is efficient and observable. Your work enables feature teams to ship independently while maintaining high standards for security and performance.
What you'll do
- Build and maintain the SDK as an internal product with its own roadmap
- Design and ship authentication plumbing for real user identity
- Integrate default telemetry, error reporting, and anonymization
- Create test kits and architecture tests to protect runtime internals
- Manage Koog version bumps and format compatibility for consumers
- Set shared limits on tool output and token usage
What you'll need
- Several years of production backend experience on the JVM
- Proficiency in Kotlin, Java, Scala or similar languages
- Experience designing APIs or SDKs for other engineers
- Track record of building and maintaining stable integrations
- Strong focus on testing and observability in development
- Interest in AI agent systems and orchestration
Stack
- Kotlin
- JVM
- Koog
How you'll work
- Hybrid setup with office in Berlin or remote within Germany
- Flexible working hours
- Regular team events and company off-sites
What you get
- Stock options
- 30 vacation days plus birthday off
- Germany Transport Ticket
- Urban Sports Club membership
- Access to Blinkist and Audible
- Free language courses