Breadcrumb is the Plausible of LLM tracing. Self-hosted, open source, and built for developers who just want to understand what their agents are actually doing without the enterprise bloat of LangFuse or LangSmith. Three lines to get your app traced. An LLM watches every trace and automatically flags issues: wrong tool calls, looping agents, oversized models and cost spikes, all before you even know something's wrong. Ask questions about your traces in plain English and get charts back.