Senior Software Engineer (SDK)

About the Role This is a high-ownership engineering role at a fast-growing, open-source AI engineering platform — think of it as the Datadog for LLM observability. The platform is trusted by thousands of development teams worldwide, and the SDKs you'll own are downloaded millions of times each month , often serving as the very first touchpoint a developer has with the product. The SDKs run in production environments ranging from serverless functions to long-running agent loops. They must be rock-solid: minimal CPU and memory overhead, zero tolerance for failure, and a developer experience that feels effortless. When you ship, thousands of developers benefit the same day. What You'll Do Own the Python and TypeScript SDKs end-to-end — reliability, performance, and developer experience. Set the bar for SDK quality across the organization. Design APIs developers love — naming conventions, parameter structure, breaking-change communication, and documentation. Every detail of the DX is yours to shape. Drive OpenTelemetry-based integrations — architect and implement framework integrations across the AI/LLM ecosystem (e.g. major LLM providers, orchestration frameworks, agent runtimes). Maintain and evolve the SDK release lifecycle — versioning strategy, packaging, CI/CD pipelines, compatibility testing, and automated release management. Performance engineer the SDK — profile, identify bottlenecks, and reduce latency and memory footprint so the SDK is never the limiting factor in production. Engage the open-source community — triage GitHub issues, review external PRs, write developer-facing docs, and represent the project on public channels. Collaborate cross-functionally — work closely with product and data teams to translate platform capabilities into clean SDK abstractions. What We're Looking For Required 5+ years of professional software engineering experience, including at least 2 years building or maintaining SDKs or client libraries Proven track record designing, implementing, and shipping production-grade SDKs — API design, versioning, packaging, and release management Experience optimizing library performance: profiling, reducing latency and memory usage, improving throughput Hands-on experience with observability, tracing, metrics, or monitoring systems (OpenTelemetry experience is a strong plus) Proficiency in Python and/or TypeScript/JavaScript and the ability to write idiomatic, language-specific library code Active experience contributing to and maintaining open-source projects (GitHub issues, PR reviews, community interactions) Strong written and verbal communication skills — comfortable writing docs, engaging with developers on GitHub, and participating in public technical discourse Experience with automated testing and CI/CD pipelines for libraries (unit/integration tests, release automation, compatibility testing) Ability to work effectively in a small, distributed team across EU timezones Legal authorization to work in the EU is required — visa sponsorship is not available Ability to be onsite in Berlin approximately one week per month Nice to Have Familiarity with analytics or large-scale telemetry systems (e.g. OLAP/columnar databases such as ClickHouse) Background from companies in the developer tooling, AI/ML infrastructure, or observability space Bachelor's degree in Computer Science, Engineering, or equivalent practical experience Compensation & Benefits Salary: €90,000 – €160,000 per year, depending on experience and location Equity participation in a well-funded, high-growth startup (Seed/Series A stage) Flexible, remote-first work environment across Europe Location This role is remote-friendly across Europe (team members are based in Germany, Austria, Switzerland, the Netherlands, France, Sweden, the UK, Spain, and Poland). You'll be expected to travel to Berlin, Germany for onsite collaboration approximately once per month. Candidates must be legally authorized to work in the EU — no visa sponsorship is available. Find Jobs in Germany on Arbeitnow