LLM observability & evaluation · Traceloop

OpenLLMetry

Apache-2.0 open-source instrumentation library extending OpenTelemetry to LLM calls, usable with any OpenTelemetry-compatible backend.

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OpenLLMetry is an open-source SDK, built and maintained by Traceloop, that extends standard OpenTelemetry instrumentation to capture LLM-specific spans: prompts, completions, token usage, and latency for calls to providers such as OpenAI and Anthropic and frameworks such as LangChain. Because it emits standard OpenTelemetry data, it is not tied to any one backend; it can send traces to Traceloop's own platform or to more than twenty other observability tools that accept OpenTelemetry input, including several other tools in this category. Traceloop, the company, also offers a hosted dashboard built on top of the same instrumentation, with a generous free tier metered by monthly trace spans and a custom-priced Enterprise tier for on-premises deployment across major clouds. OpenLLMetry itself has no license cost or usage limits since it is a client-side library, not a hosted service.

At a glance

Vendor Traceloop
Pricing model Free tier + paid plans
Free tier Yes
Deployment Cloud, Self-hosted
Open source Yes (Apache-2.0)
Best for Teams that want vendor-neutral, OpenTelemetry-standard LLM instrumentation they can route to any compatible backend.

Pricing

OpenLLMetry (the SDK) is free and open source with no usage limits; the optional Traceloop hosted dashboard has a free tier metered by monthly spans, plus a custom-priced Enterprise plan.

Plan Price Notes
OpenLLMetry SDK Free Apache-2.0, works with 25+ OpenTelemetry-compatible backends
Traceloop Free Forever $0/month Up to 50K spans/month, up to 5 seats, 24-hour data retention
Traceloop Enterprise Custom 50K+ spans/month, unlimited seats, custom retention, SOC 2, on-premises deployment

Prices read from the vendor's own page on September 21, 2026. Vendors change prices; check the source before you budget.

Features

  • OpenTelemetry-native tracing for LLM calls and chains
  • Vendor-neutral: works with 25+ observability backends
  • Token usage, latency, and cost capture
  • Optional hosted Traceloop dashboard with evaluation and prompt management
  • CI/CD integration for prompt experiments
  • On-premises deployment across major clouds (Traceloop Enterprise)

Integrations

Profile last reviewed September 21, 2026

Alternatives

Langfuse Open-source LLM tracing and evaluation platform, available self-hosted for free or as a metered hosted cloud service. Arize Phoenix Open-source, local-first tracing and evaluation library for LLM and agent applications, with an optional path to Arize's commercial platform. Helicone Open-source LLM observability platform that logs and analyzes requests via a proxy or async SDK, with a free-tier hosted cloud.

OpenLLMetry in the index now

Terms to know

Data observability Continuous automated monitoring of pipelines and datasets to catch freshness, volume and quality problems early. Machine learning Building models that learn patterns from data to make predictions or decisions, rather than following hand-coded rules. LLM observability Monitoring a language model's live behavior in production, tracking its inputs, outputs, latency, cost, and failure patterns.

Related guides

How to choose an LLM observability tool Pick an LLM tool by whether you need tracing, scoring or a gateway first — most teams eventually need all three, rarely from one vendor.