Senior Software Engineer (SDK)

About the role

About the Role This is a rare opportunity to own the SDK layer of a widely adopted open-source AI engineering platform — the kind of tooling that sits at the very first touchpoint developers have with the product. The SDKs you build ship to millions of downloads per month , running in production environments ranging from serverless functions to long-running agent loops. When you ship, thousands of developers benefit the same day. The bar is high: zero-failure reliability, minimal CPU and memory overhead, and idiomatic developer experience across Python and TypeScript. You'll be the person who sets that bar and upholds it. What You'll Do Own Python and TypeScript SDKs end-to-end — reliability, performance, and developer experience. You'll drive major version rewrites and architectural improvements, including work on OpenTelemetry-based tracing. Design APIs developers love — every detail of naming, parameter structure, breaking change communication, and documentation is yours to shape. Integrate with the AI ecosystem — build and maintain integrations with LLM frameworks, model providers, and agent runtimes; keep pace with a fast-moving ecosystem. Maintain and grow open-source community health — triage GitHub issues, review pull requests, engage with contributors, and communicate clearly on public channels. Drive performance — profile, benchmark, and optimize SDK footprint across latency, memory, and throughput dimensions. Own the release lifecycle — versioning strategy, changelog communication, compatibility testing, and CI/CD automation for library releases. Collaborate cross-functionally — work closely with product and data teams across EU timezones in a small, high-trust distributed team. What We're Looking For Required: 5+ years of professional software engineering experience, with at least 2 years building or maintaining SDKs or client libraries Proven track record designing, implementing, and maintaining production-grade SDKs — including API design, versioning, packaging, and release management Experience optimizing library/SDK performance (profiling, reducing latency and memory usage, improving throughput) Hands-on experience with observability, tracing, metrics, or monitoring systems — designing or instrumenting telemetry for debugging and analytics Proficiency in at least one SDK-relevant language (Python, TypeScript/JavaScript, Go, or Java) with ability to write idiomatic, production-quality code Active open-source experience: handling GitHub issues, PR reviews, and community interactions Strong written and verbal communication skills; comfortable writing documentation and engaging publicly (GitHub, social/developer channels) Experience with automated testing and CI/CD pipelines for libraries (unit/integration testing, release automation, compatibility testing) Ability to work effectively in small, distributed EU-timezone teams Legal authorization to work in the EU — no visa sponsorship available Nice to Have: Familiarity with analytics or large-scale telemetry systems (e.g., OLAP/columnar analytics databases) Bachelor's degree in Computer Science, Engineering, or equivalent practical experience Location This is a hybrid remote role based in Europe. You'll work remotely most of the time, with the expectation of being on-site in Berlin, Germany approximately one week per month. The team spans Germany, Austria, Switzerland, the Netherlands, France, Sweden, the UK, Spain, and Poland. Compensation & Benefits Salary: $90,000 – $160,000 USD annually (or local equivalent), depending on experience and location Opportunity to have meaningful impact on a high-adoption, widely used open-source project in the AI/ML space Work within a small, senior engineering team backed by top-tier investors including Y Combinator