Senior AI Platform Engineer – Developer ; d​/f​/m

We are looking for a Senior AI Platform Engineer – Developer Experience (d/f/m) to join our Developer Experience team and help shape the shared AI platform capabilities used across engineering at Kleinanzeigen.
Kleinanzeigen is Germany’s No. 1 online classifieds platform, reaching more than 36 million users per month. With around 600 colleagues working across product, technology and business functions, we build and operate the technology behind one of Germany’s most widely used digital platforms.
As AI becomes an increasingly important part of software development, we want to move beyond individual tools and experiments and provide engineers with reliable, reusable and governed AI capabilities.
This role is focused on the platform layer behind AI-enabled engineering: how developers and agents access models, how agents interact with internal tools, how AI workloads are executed, and how these capabilities can be governed and observed at scale.
You will work on areas such as AI & MCP gateways, model-provider integrations, agent runtimes, AI observability and evaluations, governance, and developer-facing AI tooling.

• You have hands-on experience building or operating AI platform capabilities used by multiple teams or applications
• You have experience with LLM gateways or model abstraction layers, including concepts such as provider routing, fallbacks, rate limiting, caching, quotas or cost controls
• You have practical experience with AI agent development frameworks, tool calling and agentic workflows
• You have experience with MCP or similar approaches for connecting agents to tools, APIs and internal data
• You understand how to evaluate and observe LLM-powered systems, including tracing, quality evaluation, latency, usage and cost
• You have worked with model providers or platforms such as AWS Bedrock, OpenAI or comparable services
• You understand platform concerns around identity, authentication, authorization, guardrails, data protection and auditing
• You have strong software engineering fundamentals and hands-on experience building backend or platform services
• You are proficient in at least one programming language such as Java, Kotlin or Python
• You are comfortable designing and building APIs, integrations and distributed services
• You have experience with cloud infrastructure, ideally AWS, and understand concepts such as containers, networking, identity and service-to-service communication
• You are familiar with modern infrastructure and delivery practices such as Kubernetes, Terraform and CI/CD
• You are comfortable working in an area where technologies and patterns are still evolving and can make pragmatic technical decisions under uncertainty
• Strong communication skills in English. German is a plus

• Experience with agent runtimes or secure sandbox environments
• Experience with context engineering, RAG, embeddings, retrieval or reranking
• Experience building AI SDKs, CLIs, templates or developer workflows
• Experience with internal developer platforms or developer tooling

• Design and build shared AI platform capabilities that can be used by engineering teams across Kleinanzeigen
• Build and evolve a unified way for developers, applications and agents to access approved AI models and providers
• Develop AI Gateway capabilities such as model routing, rate limiting, caching, fallbacks, quotas, usage attribution and cost controls
• Evaluate and integrate new models and model providers and help define how they can be introduced into our engineering ecosystem
• Build and evolve MCP Gateway capabilities that allow agents to securely discover and interact with internal tools and data
• Contribute to agent runtime and secure execution capabilities for AI-powered workflows
• Build…