The Best AI LLM Observability Tools in 2026
We researched AI LLM observability tools from official websites, including pricing pages, plan tables, and product documentation. Products are ranked on their core monitoring job, value for money, and verified features for tracing, cost, latency, failures, and output quality in language-model applications.
Our top picks
-
Top ranked
Arize Phoenix#1 of 239.4/10A free, open-source platform spanning tracing, evaluation, prompts, and cost tracking.
Free plan
-
Runner-up
Arize AX#2 of 239.3/10A broad LLM observability platform with meaningful free usage and self-hosted Enterprise deployment.
Free plan
-
Top-ranked free plan
Langfuse#3 of 239.2/10A broad observability platform with open-source deployment and a $29 monthly Core plan.
Free plan
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
The full ranking 23 tools, best first
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Best forTeams wanting free, open-source observability
A free, open-source platform spanning tracing, evaluation, prompts, and cost tracking.
- Token cost tracking
9.4/10★★★★★Visit Arize Phoenix -
Best forOrganizations needing full-stack LLM observability
A broad LLM observability platform with meaningful free usage and self-hosted Enterprise deployment.
- Token cost tracking
9.3/10★★★★★Visit Arize AX -
Best forTeams seeking affordable open-source LLM observability
A broad observability platform with open-source deployment and a $29 monthly Core plan.
- Token cost tracking
9.2/10★★★★★Visit Langfuse -
Best forTeams wanting low-cost cloud or self-hosted coverage
A broad, low-cost observability stack for tracing, evaluation, prompts, agents, and model costs.
- Token cost tracking
9.1/10★★★★★Visit Opik -
Best forLangChain-centric production teams
A broad LLM observability platform with strong LangChain alignment and flexible deployment.
- Token cost tracking
9.0/10★★★★☆Visit LangSmith -
Best forEstablished teams needing broad evaluation coverage
Broad tracing, evaluation, experimentation, and monitoring for established AI teams.
- Token cost tracking
8.9/10★★★★☆Visit W&B Weave -
Best forDevelopers wanting broad SDK and agent support
Broad tracing, evaluation, agent support, and deployment options for AI engineering teams.
- Token cost tracking
8.8/10★★★★☆Visit LangWatch -
Best forTeams focused on prompt lifecycle management
A strong fit for teams that need prompt versioning, testing, and multi-provider observability.
8.7/10★★★★☆Visit Agenta -
Best forEvaluation-led engineering teams
A strong choice for teams that make evaluation and regression control central to LLM development.
8.6/10★★★★☆Visit Braintrust -
Best forTeams needing gateway and observability features
A broad LLM gateway and observability platform with cloud and self-hosted options.
- Token cost tracking
8.5/10★★★★☆Visit Helicone -
Best forTeams prioritizing evaluations and runtime guardrails
Galileo connects offline evaluation, production tracing, regression gates, and runtime guardrails.
8.4/10★★★★☆Visit Galileo -
Best forEnterprise teams needing guardrails and governance
A broad observability and governance platform for teams operating LLM and agent systems.
- Token cost tracking
8.3/10★★★★☆Visit Fiddler AI -
Best forTeams with complex agent workflows
A broad toolkit for tracing, evaluating, deploying, and monitoring complex AI agents.
- Token cost tracking
8.2/10★★★★☆Visit HoneyHive -
Best forSelf-hosters needing broad provider coverage
A broad, self-hosted observability stack for teams building LLM apps and agents.
- Token cost tracking
8.1/10★★★★☆Visit OpenLIT -
Best forTeams combining prompt testing and observability
A broad AI lifecycle toolkit for teams combining prompt testing with production observability.
8.0/10★★★★☆Visit Maxim AI -
Best forTeams needing routing plus request observability
Portkey combines LLM routing, tracing, cost analytics, and prompt management.
- LLM trace capture
- Output evaluations
- Latency metrics
7.9/10★★★★☆Visit Portkey -
Best forOpen-source teams focused on deep trace inspection
A detailed, open-source tracer for teams that need deep visibility into LLM and agent execution.
- Token cost tracking
7.8/10★★★★☆Visit MLflow -
Best forTeams centered on rigorous LLM evaluation
A broad evaluation and observability suite for teams that need rigorous LLM quality controls.
7.7/10★★★★☆Visit Confident AI -
Best forLarge teams needing an integrated model gateway
A broad observability suite with gateway controls for teams building LLM applications.
- Token cost tracking
7.6/10★★★★☆Visit Respan -
Best forTeams prioritizing prompt operations and testing
A focused platform for managing, testing, and monitoring prompts across AI workflows.
7.5/10★★★★☆Visit PromptLayer -
Best forDevelopers building portable tracing instrumentation
A portable, open-source tracing toolkit for AI applications and workflows.
- Token cost tracking
7.4/10★★★★☆Visit OpenLLMetry -
Best forSelf-hosted evaluation and tracing projects
A self-hosted toolkit for tracing, evaluating, and comparing LLM applications.
7.2/10★★★★☆Visit TruLens -
Best forTeams wanting low-cost paid observability
Low-cost paid observability for teams tracing, evaluating, and improving LLM applications.
- Token cost tracking
7.1/10★★★★☆Visit Lunary
No tools match those filters.
Compare at a glance
| # | Tool | Free plan | Paid from | Token cost tracking | Score |
|---|---|---|---|---|---|
| 1 | Arize Phoenix | Yes | Free | Yes | 9.4 |
| 2 | Arize AX | Yes | $50/mo | Yes | 9.3 |
| 3 | Langfuse | Yes | $29/mo | Yes | 9.2 |
| 4 | Opik | Yes | $19/mo | Yes | 9.1 |
| 5 | LangSmith | Yes | $39/seat/mo | Yes | 9.0 |
| 6 | W&B Weave | Yes | $60/mo | Yes | 8.9 |
| 7 | LangWatch | Yes | €29/seat/mo | Yes | 8.8 |
| 8 | Agenta | Yes | $29/mo | 8.7 | |
| 9 | Braintrust | Yes | $249/mo | 8.6 | |
| 10 | Helicone | Yes | $79/mo | Yes | 8.5 |
| 11 | Galileo | Yes | $100/mo | 8.4 | |
| 12 | Fiddler AI | Yes | $0.002/unit usage-based | Yes | 8.3 |
| 13 | HoneyHive | Yes | Yes | 8.2 | |
| 14 | OpenLIT | Yes | Free | Yes | 8.1 |
| 15 | Maxim AI | Yes | $29/seat/mo | 8.0 | |
| 16 | Portkey | Yes | $49/mo | Yes | 7.9 |
| 17 | MLflow Tracing | Yes | Free | Yes | 7.8 |
| 18 | Confident AI | Yes | $200/mo | 7.7 | |
| 19 | Respan (formerly Keywords AI) | Yes | $199/mo | Yes | 7.6 |
| 20 | PromptLayer | Yes | $49/mo | 7.5 | |
| 21 | OpenLLMetry | Yes | Free | Yes | 7.4 |
| 22 | TruLens | Free | 7.2 | ||
| 23 | Lunary | No | $20/user/mo | Yes | 7.1 |
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How we rank AI LLM observability tools
Every tool on this page was researched by iTechGuides Editors from its official website — pricing pages, plan tables and product documentation. We rank on how well each one does this category's core job, what the free or entry plan includes, and where it falls short. Where we have enough verified facts, the score out of 10 is a rubric — job fit, value and how much we could verify — shown with its breakdown on every tool's page; a tool we have not verified enough to score yet shows its rank without a number. Scores are re-checked when a product changes its plans. Read the full editorial policy, or submit a tool we missed.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Last updated · How we research and update