Senior Frontend Engineer
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 looking for a senior frontend engineer to build the UI for the most widely adopted open source LLM engineering platform where the core challenge is rendering massive, data-intensive views fast and making complex workflows feel simple.
Requirements
- Strong in React, TypeScript, and modern CSS
- Likes to collaborate with a designer to turn complex requirements into intuitive interfaces
- Someone who can PM and project-manage themselves
- Interest in open source software and genuine enjoyment talking to users about their experience
- Thrives in a small, accountable team where your output is visible and matters
Benefits
- Flexible remote work policy
- Opportunity to work on a high-impact project
- Opportunity to learn and grow with a small, experienced team
- Regular feedback and support from the team
- Continuous learning journey in the AI space
