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AI/DATA/LLM OBSERVABILITY TOOLS/LLM OBSERVABILITY TOOLS WITH A FREE PLAN

Best LLM observability tools with a free plan

10 AI tools ranked, each with a short verdict.

VERIFIEDLISTER SCORE · UPDATED REGULARLY

Best LLM observability tools with a free plan: Top 10 Ranked. LangFuse ranks first, with a Lister Score of 92.0.

LangFuse takes the top spot on this list: it utilises ClickHouse to query millions of traces reliably at enterprise scale. Arize AI is built for AI engineers building production agents, and traces everything using the leading open standard for GenAI observability. Fiddler AI serves Enterprise security and compliance teams.
RANKENTRYSCORETRENDFROM
1LangFuseBuilt for AI engineering teams building production-grade LLM applications92.0NEW–
2Arize AIIntegrates with over forty models, frameworks, and AI tools88.0NEWCustom
3Fiddler AIFiddler AI is an enterprise control plane for agentic and predictive systems88.0NEWCustom
4ManifestAutofixes bad requests on the fly to ensure zero downtime88.0NEW–
5OpenRouterProvides higher availability via distributed infrastructure88.0NEW–
6ZywrapSupports switching between sixty-five models from fourteen providers seamlessly88.0NEW–
7MemoriIs model-agnostic so memory persists across different LLM providers without loss86.0NEW–
8axemBuilt for critical industries84.0NEW–
9MLflow AI PlatformBuilt for organizations powering LLMOps and MLOps workflows82.0NEW–
10PromptLayerAllows visual editing and deployment of prompts without application redeployment82.0NEW–
CURATED · UPDATED REGULARLYHOW WE RANK →

The ranking, in detail

01

LangFuse

Open source agent evals and observability platform

Langfuse is an open-source AI engineering platform for agent evaluations and observability. It enables teams to trace, evaluate, and improve AI agents using a unified system.

Best for: AI engineering teams building production-grade agents
92.0
02

Arize AI

ML observability and fairness monitoring platform

Arize AI is an agent observability and evaluation platform. It turns production signals into continual learning so agents improve with every interaction.

Best for: Mid-market to enterprise organisations with complex ML deployments requiring fairness and compliance monitoring
88.0
03

Fiddler AI

Model monitoring and explainability platform for compliance

Fiddler AI is an enterprise control plane for agentic and predictive systems. It provides unified observability, policy enforcement, and governance across the entire AI lifecycle.

Best for: Data science teams and enterprises prioritising model transparency and fairness compliance
88.0
04

Manifest

The open source LLM gateway for reliable AI agents

Manifest is an open source LLM gateway that enables builders to create reliable AI agents. It assists teams in managing inference consumption and monitoring usage effectively.

Best for: AI builders and teams
88.0
05

OpenRouter

The unified interface for every model

OpenRouter is a unified interface for every model. It offers better prices and uptime without subscriptions.

Best for: AI native startups and growing teams
88.0
06

Zywrap

Ship AI features without writing the prompt

Zywrap provides a library of over fourteen thousand pre-written and tested AI prompts. Users select a task, supply input fields, and receive structured output without writing code.

Best for: developers and SaaS teams
88.0
07

Memori

Agent-native memory infrastructure governed for the enterprise

Memori is an agent-native memory infrastructure that turns execution traces into procedural memory. It enables long-running agents to learn from every run and stop repeating errors.

Best for: Enterprise AI engineering teams
86.0
08

axem

Sovereign AI platform

Axem is an open-source sovereign AI platform. It allows users to run LLMs and agents entirely in-house on controlled infrastructure.

Best for: critical industries
84.0
09

MLflow AI Platform

Deliver high-quality AI, Fast

MLflow AI Platform is the leading open source AI engineering platform for agents and models. It enables teams to debug, evaluate, monitor, and optimise production-quality AI applications with confidence.

Best for: organizations powering LLMOps and MLOps workflows
82.0
10

PromptLayer

The collaboration layer for AI engineering teams

PromptLayer is an AI engineering platform combining a prompt registry with evaluations and observability. It enables teams to version, test, deploy, and monitor prompts effectively.

Best for: AI engineering teams
82.0
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Frequently asked questions

What are the best LLM observability tools with a free plan?

LangFuse ranks first on Lister. Langfuse is an open-source AI engineering platform for agent evaluations and observability. It enables teams to trace, evaluate, and improve AI agents using a unified system.

What are the top 10 LLM observability tools with a free plan?

1. LangFuse; 2. Arize AI; 3. Fiddler AI; 4. Manifest; 5. OpenRouter; 6. Zywrap; 7. Memori; 8. axem; 9. MLflow AI Platform; 10. PromptLayer.

Are there free options for LLM observability tools with a free plan?

No free option is confirmed in the recorded pricing for this ranking. Check each provider's pricing page for current plans and trials.

What do the top four say they are built for?

LangFuse says it is built for AI engineering teams building production-grade LLM applications, and Arize AI for AI engineers building production agents. Fiddler AI says it is built for Enterprise security and compliance teams, and Manifest for AI builders and teams.

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