LangWatch is a platform for LLM evaluations and AI agent testing that lets teams test, simulate, evaluate and monitor LLM-powered agents across the full lifecycle. Its observability layer captures and lets teams search every LLM interaction across environments to debug failures, investigate incidents and support audits, while its evaluation and simulation tools verify agent quality before release. The open-core product helps engineering and product teams ship reliable AI applications. Based in Amsterdam, LangWatch raised roughly €1M in pre-seed funding led by Passion Capital, with participation from Volta Ventures and Antler.