Senior Backend Engineer - Kotlin (m/f/d) - Agent SDK

voize; Berlin; Híbrido; EUR 90 000 - 130 000; Tempo integral

Vantagens oferecidas por esta oferta de emprego

Stock options

30 vacation days + birthday off

Germany Transport Ticket and wellness

Resumo da oferta

voize is seeking a Senior Backend Engineer to build and maintain the Kotlin foundation for our AI agent SDK. You will own the internal SDK surface, define the identity layer, and ensure telemetry and observability from day one.

You will work across squads to align on contracts, versioning, and tool limits, enabling rapid shipping while maintaining quality and security. Berlin-based or remote within Germany is supported.

Qualificações

• Several years building production backend systems in Kotlin.
• Testing and observability are part of how you build.
• You are drawn to AI agent systems and the orchestration work underneath them.
• You bring teams with you and communicate clearly in English.

Responsabilidades

• Build and maintain the Kotlin-based SDK as an internal product.
• Design and ship the identity/auth plumbing as needed.
• Ensure telemetry and error reporting are integrated from launch.
• Work with Koog versioning and tool-output limits across the SDK.
• Coordinate with multiple squads to gather consumer needs.

Conhecimentos

Kotlin backend

Testing and observability

AI agent systems

Cross-team collaboration

Clear English communication

Ferramentas

Telemetry tooling

Evaluation harness

SDK versioning

Descrição da oferta de emprego

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.

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: Build the layer every agent moves onto

As Senior Backend Engineer on the team behind our Agent SDK, you build and maintain the Kotlin foundation that our AI agents move onto. Agents have grown into a product surface across verticals and markets, and the layer underneath them needs a permanent owner. Your work makes the cost of the second and third agents visibly less than the first, so feature teams can ship at their own pace.

Your Daily Business - No two days are alike

• Build and maintain the SDK as an internal product. You shape the runtime and the client-facing contracts that consuming teams build on. The SDK has a roadmap of its own, and you help set it.
• You build the identity layer that agents run on , so customer-facing agents can write with a real user identity. Your responsibilities may include designing and shipping the auth plumbing, depending on what we have already built by your start date.
• Make every agent observable from the day it launches. You wire telemetry and error reporting into the SDK by default, and you integrate inference and anonymization so the SDK enforces them for every consumer.
• Build the test kit that the SDK still needs. You create it along with the architecture tests that protect the runtime internals, and you build the path that runs every SDK agent against our ML team’s evaluation harness before a model change ships.
• Absorb ecosystem change on behalf of consuming teams. You own Koog version bumps and format compatibility, and you set the shared limits on tool output and token usage, so an upgrade lands once in the SDK and reaches everyone from there.

Your Skillset - What you bring to the table

• Several years building production backend systems in Kotlin, including something other engineers consume. An SDK or an internal platform where the contract you publish is the product, and where you have lived with the versioning work that follows.
• Testing and observability are part of how you build. You have set up the tooling that makes a codebase comfortable for other people to work in.
• You are drawn to AI agent systems , and to the orchestration and evaluation work underneath them. Whether from work or your own projects, you are close enough to the space to know where it gets hard.
• You bring teams with you. Much of this work reaches squads across engineering, so you gather what consumers need and make your reasoning easy to follow. You communicate clearly in English.

Growing together - what you can expect at voize

• We are a fast-growing startup, that means you will take on real problems, 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.

Ready to talk?

We look forward to your application and can’t wait to meet you - no matter who you are or what background you have!