Langfuse

Langfuse is an open-source LLM observability platform for teams building AI applications. It helps developers trace model calls, inspect prompts, measure latency and cost, evaluate outputs, and understand how real users interact with AI features in production. As AI applications move from prototype to production, teams need visibility into what the model is doing, where failures happen, how much each workflow costs, and whether outputs are improving over time. Langfuse gives developers tools for tracing, prompt management, dataset creation, evaluations, analytics, and debugging across LLM-powered products. The product is especially useful for SaaS teams, AI startups, and technical founders building chatbots, agents, RAG systems, support copilots, research tools, or internal automation workflows. Instead of guessing why an AI workflow failed, teams can inspect the full chain of prompts, responses, metadata, scores, and user feedback. Langfuse can be used as a hosted cloud product or self-hosted for more control. That makes it relevant for both indie builders who want fast observability and teams with stricter data requirements. For FutureStack, Langfuse belongs in Developer Tools because it supports the invisible but critical part of AI product development: monitoring quality, cost, reliability, and prompt behavior after launch.