Free and open first
Best AI Agent Observability Tools in 2026
AI agent observability tools let you examine agent activity through traces, sessions, and usage information. Compare agent framework support with prompt and tool tracing, session replay, and trace retention to see what visibility each option publishes. Cost tracking and deployment options add operational considerations, while free-plan availability and paid-from pricing help you weigh access and cost. PetalTrace, OpenLIT, and W&B Weave are among the entries to consider. Think about what you need to inspect during agent runs and how long that information should be retained, then compare those needs with the listed capabilities.
- 31 apps
- Research read 23 Sept 2026
- How the order is worked out
- 1
Agenta
Free plan Open source APISelf-hostedWebAgenta combines agent-building, automation, and run observability, with both cloud and self-hosted options.
- 2
AgentOps
Free plan Open source APISelf-hostedWebAgentOps brings tracing, replay, audit trails, and cost monitoring together for agent applications, with broad framework and provider integrations.
- 3
Langfuse
Free plan Open source APILinuxSelf-hosted+1Langfuse brings tracing, prompt workflows, and evaluation features into one AI engineering platform, with both hosted and self-hosted options.
- 4
LangWatch
Free plan Open source APILinuxMac+2LangWatch brings agent simulation, evaluation, tracing, and deployment options together for teams working toward production.
- 5
MLflow Tracing
Free plan Open source APILinuxSelf-hosted+1Choose MLflow Tracing if you need free, open-source tracing with detailed spans and broad LLM framework integrations, while keeping trace data on your infrastructure.
- 6
Lunary
Free plan Open source APISelf-hostedWebLunary combines LLM observability with analytics, prompt management, and response evaluation.
- 7
OpenLIT
Free plan Open source APILinuxMac+3Choose OpenLIT if you want LLM tracing, evaluations, prompt tools, and cost tracking, with the option to self-host under an Apache 2.0 license.
- 8
Opik
Free plan Open source APILinuxMac+3Opik brings tracing, evaluation, testing, and production monitoring into one platform, with both cloud and self-hosted options.
- 9
W&B Weave
Free plan Open source APIiPhoneLinux+4W&B Weave brings tracing, evaluation, monitoring, and safety scoring together for production AI agents.
- 10
Traceloop
Free plan Open source APISelf-hostedWebTraceloop brings tracing, evaluation, and release checks together, with OpenLLMetry available for exporting observability data.
- 11
Arize AX
Free plan APISelf-hostedWebArize AX combines tracing, evaluations and experiments with tools for investigating agent failures.
- 12
Arize Phoenix
Free plan APISelf-hostedWebPhoenix brings tracing, evaluation, prompt inspection, and dataset experiments to AI application teams. It is free and open source, with deployment choices and usage management left to users.
- 13
Braintrust
Free plan APISelf-hostedWebBraintrust combines production trace inspection with dataset evaluations and prompt iteration.
- 14
Fiddler AI
Free plan APISelf-hostedWeb - 15
Galileo
Free plan APISelf-hostedWebGalileo combines evaluation, observability, and guardrails with several deployment options and developer interfaces. Check the trace allowance and SSO availability against your deployment needs.
- 16
Helicone
Free plan APISelf-hostedWebHelicone brings routing and observability tools together, with a free tier and self-hosting options. Its maintenance-mode status is worth weighing when considering it for a new deployment.
- 17
HoneyHive
Free plan APISelf-hostedWebHoneyHive covers trace inspection, evaluations, live monitoring, and version experiments for AI agents. Teams should compare the free plan’s limits with their event volume and retention needs.
- 18
LangSmith
Free plan APILinuxMac+3LangSmith combines agent evaluation with prompt tools and observability, including cost and trajectory tracking.
- 19
Laminar
Free plan APISelf-hostedWebChoose Laminar if you need OpenTelemetry-native tracing and debugging for AI agents, with evaluations and cloud or self-hosted deployment options.
- 20
LogicGaze
Free plan APISelf-hostedWebChoose LogicGaze if your team needs LLM tracing combined with evaluations, guardrails, cost controls, and security scans.
- 21
Maxim AI
Free plan APISelf-hostedWebMaxim AI brings prompt work, agent evaluation, and production observability into one platform.
- 22
PetalTrace
Free plan APILinuxMac+3PetalTrace brings tracing, cost analysis, run comparison and replay into one developer-facing toolset. Teams considering deployment should account for authentication being disabled by default.
- 23
Hexel
Free plan APIHexel combines pre-execution policy checks with traces, run replay, and several execution planes.
- 24
SigNoz
Free plan AndroidAPIiPhone+2SigNoz brings monitoring signals, querying, alerting, dashboards, and tracing into one observability tool.
- 25
Respan (formerly Keywords AI)
Free plan APISelf-hostedWebRespan combines model routing with tracing, evaluation, and monitoring in one product. Check the gateway's possible latency and plan terms against your requirements before choosing it.
#1Places #1, #2, #3, #4, #5 on this list can be bought by the makers of the software on it. See the price
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