arize.com · Observability
Free, self hostable tracing and evaluation tool built on OpenTelemetry, source available under the Elastic License 2.0. Arize became part of Dynatrace in October 2026.
Arize Phoenix is one of 10 observability tools on TrueIQ. See all observability tools or how we check facts.
// guides
How to use LangSmith with LangGraph: set four environment variables, read node traces and threads, then score your graph and single nodes on a dataset.
Is LangSmith API free? Yes: API keys and the REST API cost nothing, and the Developer plan covers 5,000 traces a month. See key types, limits and overage costs.
Is Langfuse free for commercial use? Yes: the MIT core can be self hosted in paid products at no cost. See what needs a license key and when the cloud bills.
Datadog LLM Observability vs Langfuse: how each bills (LLM spans vs units), retention, self hosting, evals and setup, with worked cost examples for 2026.
AI agent observability explained: trace tool loops, permissions and memory, the six PAI telemetry gaps, and which tools fit, from Langfuse to Datadog.
The best LLM observability tools in 2026 compared: Langfuse, LangSmith, Phoenix, Opik, Weave and more, with licenses, self hosting and who now owns what.
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