PandaProbe

PandaProbe is purpose-built for AI agent developers who need to understand what's happening inside multi-step agent behaviors. Its uncertainty detection over long trajectories is a standout—most LLM monitoring tools focus on single-turn latency and token counts, while PandaProbe tracks decision quality and drift across entire sessions. The one-line instrumentation for frameworks like LangGraph, CrewAI, and the Google ADK makes setup fast. The free Hobby tier (100 traces/month) is generous enough for small projects or evaluation, and the open-source self-hosted option (Apache 2.0) gives teams full control without usage limits. Where it falls short: if you only need basic single-turn LLM monitoring, simpler tools like LangSmith or Helicone may be easier. The CLI and Skill are powerful but require some technical comfort; non-developer teams may struggle. Paid tiers are priced reasonably for the depth of metrics, but the pay-as-you-go overage model can surprise users with sudden cost spikes if not monitored. Compared to Arize AI or WhyLabs, PandaProbe is more agent-centric and less generic ML monitoring. For agent-first teams shipping production systems, it's a solid choice—especially if you value open-source flexibility and research-grade evaluation.