Langfuse

Langfuse is the open-source LLM engineering platform designed to help teams build production-grade LLM applications faster.Langfuse addresses these challenges by providing an open-source platform to debug and improve LLM applications. Langfuse captures the full context of your application, tracing the complete execution flow—including API calls, retrieved context, prompts, parallelism, and more. By enabling hierarchical representations through nested traces, Langfuse helps you understand complex logic built around LLM calls. Langfuse also offers full **multi-modal** support, including audio, images, and attachments.Metrics & QualityLangfuse measures cost and latency, breaking down metrics by user, session, feature, model, and prompt version, allowing for detailed analysis. To assess output quality, Langfuse facilitates the collection of user feedback, performs automated LLM-as-a-judge evaluations, and supports manual data labeling within the platform. It also offers **prompt management** features, allowing you to handle prompts effectively and perform **prompt experiments** over new ideas and systematically track success.Testing & ExperimentationFor testing and experimentation, Langfuse supports versioning your application and running tests of expected inputs and outputs via curated datasets. This provides quantitative insights into the impact of changes, helping you understand and improve your LLM applications more effectively.