List of the Best LLM Observability & Evaluation Software in 2026

What is Langfuse?

Langfuse is an open-source LLM engineering platform for tracing, evaluation, prompt management, and metrics. It provides detailed traces of LLM application executions — capturing every LLM call, tool use, retrieval step, and agent action — and links traces to user sessions for production ...

What is Helicone?

Helicone is an open-source LLM observability platform that works as a proxy — developers route their LLM API calls through Helicone's gateway with a single URL change, and it automatically logs every request, tracks cost and latency, enables prompt caching, and provides rate limiting. ...

What is LangSmith?

LangSmith is the LLMOps observability and evaluation platform built by LangChain for teams developing production LLM applications. It provides tracing, debugging, and evaluation for any LLM application — not just LangChain ones. Developers use LangSmith to trace every LLM call and tool ...

What is Traceloop?

Traceloop provides LLM observability built on OpenLLMetry, its open-source OpenTelemetry extension for generative AI. Because the instrumentation is standard OpenTelemetry, traces flow into existing observability backends such as Datadog, Honeycomb or Grafana rather than requiring a separate ...

What is Opik?

Opik is Comet's open-source platform for tracing, evaluating and monitoring LLM applications, covering development-time experimentation and production monitoring in one tool. It records traces across chains and agents, supports LLM-as-judge and heuristic evaluators, and can gate CI on ...

What is Arize Phoenix?

Phoenix is Arize's open-source observability and evaluation tool for LLM applications, built on OpenTelemetry so traces are portable rather than locked to one vendor. It runs locally in a notebook or as a self-hosted service, capturing spans across retrieval, prompting and tool calls, and ...

What is Patronus AI?

Patronus AI focuses on automated evaluation of LLM systems, scoring outputs for hallucination, safety and domain-specific criteria using purpose-trained evaluator models rather than general-purpose LLM judging. It supports adversarial test generation to find failures before release and ...

What is Lunary?

Lunary is an open-source observability platform for LLM applications, covering request logging, tracing across chains and agents, prompt versioning and per-user analytics. It supports self-hosting and includes guardrails for detecting problematic content. It is positioned for teams that want ...

What is TruLens?

TruLens is an open-source library for evaluating and tracing LLM applications, built around programmatic feedback functions that score outputs for groundedness, context relevance and answer relevance — the triad it uses to diagnose retrieval-augmented generation. Instrumentation is added in ...

What is HoneyHive?

HoneyHive provides observability and evaluation for production AI applications, combining distributed tracing across agent steps, online and offline evaluation, dataset curation from real traffic, and prompt management in one platform. Curating evaluation datasets directly from production ...

What is Freeplay?

Freeplay is an operations platform for teams building AI features, covering prompt management and versioning, batch testing, human review workflows and production monitoring. Its emphasis is collaboration between engineers and the domain experts who judge whether output is actually good, giving ...

What is Maxim AI?

Maxim AI covers the agent lifecycle from prompt experimentation through simulation and evaluation to production observability. Its simulation capability runs agents against generated user personas and scenarios to surface multi-turn failures that single-prompt evaluation misses — an agent can ...

What is Portkey?

Portkey is a gateway that sits between an application and model providers, adding routing and automatic fallback across models, semantic caching, rate limiting, guardrails and cost tracking, with observability over every request. Because it sits in the request path it captures traces without ...

What is LangWatch?

LangWatch provides testing, evaluation and monitoring for LLM agents, with tracing across agent steps, automated evaluation including scenario-based agent testing, and prompt optimisation using DSPy. It is open-source with a self-hosted option and is framework-agnostic across common agent ...

What is Galileo?

Galileo is an LLM evaluation and observability platform for testing, monitoring, and guardrailing generative AI applications and agents. It captures traces from an application and scores them using its proprietary evaluation models against research-backed metrics, converting offline evals into ...

What is Braintrust (AI Observability)?

Braintrust is an evaluation and observability platform for teams building production LLM applications and agents. It lets engineers log and trace LLM calls with latency, token, and cost metrics, run structured evals against datasets to score output quality, and replay logged production traces ...

What is Athina AI?

Athina AI provides evaluation and monitoring for LLM applications, with a library of preset evaluators, support for custom ones, and dataset management for running experiments before shipping a prompt or model change. It offers a self-hosted deployment so prompts and completions stay inside the ...

What is Confident AI?

Confident AI is the platform built around DeepEval, an open-source evaluation framework that treats LLM testing like unit testing — assertions over metrics such as faithfulness, answer relevance and contextual precision, runnable in CI. The hosted platform adds dataset curation, regression ...

What is PromptLayer?

Unveiling PromptLayer, the pioneering platform tailored for prompt engineers. This innovative tool is tailored to tackle the complexities that accompany managing GPT requests, marking a paradigm shift in how you analyze, troubleshoot, and delve into these requests. With PromptLayer, you wield ...

What is Comet?

Comet is a machine learning experiment tracking and model monitoring platform that integrates with any ML library via a single line of code. It covers the full ML lifecycle from experiment management to production monitoring, and works on both local machines and cloud environments. Data ...