Senior Software Engineer (SDK)
LangfuseBerlin, Germany • London, England, United Kingdom • Munich, Bavaria, Germany • Paris, Ile-de-France, France • Zurich, Zurich, Switzerland
Posted February 17, 2026
Full Time
About the Company
Langfuse is an open‑source observability platform that enables teams to develop, monitor, evaluate, and debug large language model (LLM) applications. It offers SDKs for Python and JavaScript, a unified dashboard, and tools for prompt management, automated testing, and human‑in‑the‑loop annotation, allowing developers and product managers to track cost, latency, and user feedback. The platform is self‑hosted in minutes and already trusted by thousands of users, from YC startups to enterprises such as Khan Academy and Twilio, for its reliability and performance. Langfuse’s distinctive value lies in its tight integration with popular LLM frameworks (OpenAI, LangChain, Llama‑Index, Vercel AI SDK) and its community‑driven open‑source ecosystem that fuels rapid iteration and continuous improvement.
Job Description
We're building the 'Datadog' of AI applications, and we're looking for a Senior Software Engineer to lead our SDK engineering efforts. As a key member of our team, you'll have a significant impact on the developer experience, API design, and reliability of our SDKs.
Requirements
- Strong engineer who gets excited about developer experience, API design, and writing code that runs reliably in other people's production systems
- Experience building or maintaining SDKs, client libraries, or developer tools
- Deep understanding of performance: ability to profile, benchmark, and minimize CPU/memory overhead in hot paths
- Thoughtful about versioning, backwards compatibility, and migration paths
Benefits
- Generous Paid Time Off
- 401k Matching
- Tuition Reimbursement
- Relocation Assistance
