Senior Software Engineer (SDK)

Stack

Responsibilities

• ▹Own the Python and TypeScript SDKs (built on OpenTelemetry): reliability, performance, developer experience, batching, async flushing, graceful degradation
• ▹Design APIs developers love: naming, parameter structure, breaking-change communication, documentation quality
• ▹Integrate with 40+ AI frameworks and model providers: OpenAI SDK, Vercel AI SDK, LangChain, LlamaIndex, Pydantic AI, OpenAI Agents, CrewAI, Amazon Bedrock AgentCore, LiveKit, and more
• ▹Maintain the OpenTelemetry (OTLP) endpoint, extending language support to Java, Go, and any language with an OpenTelemetry SDK
• ▹Write public SDK documentation, integration guides, and migration paths

Requirements

• ▹Strong engineer excited about developer experience, API design, and code that runs reliably in other people's production systems
• ▹Experience building or maintaining SDKs, client libraries, or developer tools, ideally in Python and/or TypeScript
• ▹Deep understanding of performance: profiling, benchmarking, minimizing CPU/memory overhead in hot paths
• ▹Able to manage projects yourself, with strong conviction about what to build and how to ship it
• ▹Thoughtful about versioning, backwards compatibility, and migration paths
• ▹Interest in open source and genuine excitement about developers' integration challenges
• ▹CS or quantitative degree preferred

Nice to have

• ▹Experience with OpenTelemetry internals or observability instrumentation
• ▹Former founder or early startup experience
• ▹Contributions to popular open source SDKs or developer tools
• ▹ML/AI background or familiarity with the LLM framework ecosystem

Soft skills

About the company

Langfuse is an open source LLM engineering platform (tracing, evaluation, prompt management) whose SDKs are downloaded 26M+ times a month, now part of ClickHouse. A small, engineering-heavy team based in Berlin and San Francisco, also hiring in EU timezones with one week per month in the Berlin office.