Best LLM Observability Tools in 2026
Updated
In short: Evidently AI is ranked #1 of 26 as of 7 October 2026, ahead of W&B Weave and Opik. The best-ranked option with a free plan is W&B Weave. The lowest first paid tier on this page is Respan (formerly Keywords AI) at $16.58/mo.
When you need visibility into an LLM application, compare what each tool can trace and how it handles evaluation and prompt work. Agent tracing, LLM tracing, and retrieval tracing describe different parts of the activity you may want to inspect; LLM evaluations and prompt management add other oversight dimensions. Token cost tracking can help you assess usage alongside deployment options, free-plan availability, and paid-from pricing. Evidently AI, W&B Weave, and Opik are among the named options to compare. Check which listed capabilities match the signals you need to monitor, and weigh how each tool’s deployment and plan details fit your setup.
26 LLM observability tools ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
26ranked
21free plans on this page
$16.58/molowest paid tier
7 Oct 2026last checked
Input list LLM Observability Tools 25 channels on this page · 131 of 200 spec lines stated by the makers
Ch Tool Free planPaid fromLLM tracingLLM evaluationsPrompt managementAgent tracingRetrieval tracingToken cost tracking Spec sheet Score
01 Evidently AI Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingnot statedToken cost trackingnot stated 5/8spec lines stated 7.9
02 W&B Weave Free planYesPaid from$60/moLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 8/8spec lines stated 7.9
03 Opik Free planYesPaid from$19/moLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 8/8spec lines stated 7.6
04 OpenLIT Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 7/8spec lines stated 7.5
05 Helicone Free planYesPaid from$79/moLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 8/8spec lines stated 7.4
06 Promptfoo Free planYesPaid fromnot statedLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 1/8spec lines stated 7.4
07 Respan (formerly Keywords AI) Free planYesPaid from$199/moLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 8/8spec lines stated 7.4
08 Maxim AI Free planYesPaid fromnot statedLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 1/8spec lines stated 7.3
09 LangWatch Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 7/8spec lines stated 7.2
10 Fiddler AI Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 7/8spec lines stated 7.1
11 Giskard Free planYesPaid fromnot statedLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 1/8spec lines stated 7.1
12 Laminar Free planYesPaid from$30/moLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 8/8spec lines stated 7.1
13 Langfuse Free planYesPaid from$29/moLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 8/8spec lines stated 7.1
14 LangSmith Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 7/8spec lines stated 7.1
15 Arize AX Free planYesPaid from$50/moLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 8/8spec lines stated 7.0
16 Arize Phoenix Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 7/8spec lines stated 7.0
17 Galileo Free planYesPaid from$100/moLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 2/8spec lines stated 7.0
18 HoneyHive Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingYesToken cost trackingYes 7/8spec lines stated 7.0
19 Braintrust Free planYesPaid from$249/moLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 2/8spec lines stated 6.9
20 Parea AI Free planYesPaid fromnot statedLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 1/8spec lines stated 6.9
21 Confident AI Free planYesPaid from$200/moLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 2/8spec lines stated 6.8
22 AgentOps Free planYesPaid from$40/moLLM tracingYesLLM evaluationsnot statedPrompt managementnot statedAgent tracingYesRetrieval tracingYesToken cost trackingYes 6/8spec lines stated 6.6
23 Ragas Free planYesPaid fromnot statedLLM tracingnot statedLLM evaluationsnot statedPrompt managementnot statedAgent tracingnot statedRetrieval tracingnot statedToken cost trackingnot stated 1/8spec lines stated 6.6
24 Lunary Free planNoPaid fromnot statedLLM tracingYesLLM evaluationsYesPrompt managementYesAgent tracingYesRetrieval tracingnot statedToken cost trackingYes 6/8spec lines stated 5.8
25 OpenLLMetry Free planYesPaid fromnot statedLLM tracingYesLLM evaluationsnot statedPrompt managementnot statedAgent tracingYesRetrieval tracingYesToken cost trackingYes 5/8spec lines stated 5.7
Compare all 25 in a table
| # | Tool | Score | Free plan | From | Free plan | Paid from | LLM tracing | LLM evaluations |
|---|---|---|---|---|---|---|---|---|
| 1 | Evidently AI | 7.9 | Free plan | $80/mo | Yes | — | Yes | Yes |
| 2 | W&B Weave | 7.9 | Free plan | $60/mo | Yes | 60 /mo | Yes | Yes |
| 3 | Opik | 7.6 | Free plan | $19/mo | Yes | 19 /mo | Yes | Yes |
| 4 | OpenLIT | 7.5 | Free plan | Free | Yes | — | Yes | Yes |
| 5 | Helicone | 7.4 | Free plan | $79/mo | Yes | 79 /mo | Yes | Yes |
| 6 | Promptfoo | 7.4 | Free plan | Free | Yes | — | — | — |
| 7 | Respan (formerly Keywords AI) | 7.4 | Free plan | $16.58/mo | Yes | 199 /mo | Yes | Yes |
| 8 | Maxim AI | 7.3 | Free plan | $29/mo | Yes | — | — | — |
| 9 | LangWatch | 7.2 | Free plan | €29/mo | Yes | — | Yes | Yes |
| 10 | Fiddler AI | 7.1 | Free plan | Free | Yes | — | Yes | Yes |
| 11 | Giskard | 7.1 | Free plan | Free | Yes | — | — | — |
| 12 | Laminar | 7.1 | Free plan | $30/mo | Yes | 30 /mo | Yes | Yes |
| 13 | Langfuse | 7.1 | Free plan | $29/mo | Yes | 29 /mo | Yes | Yes |
| 14 | LangSmith | 7.1 | Free plan | $39/mo | Yes | — | Yes | Yes |
| 15 | Arize AX | 7.0 | Free plan | $50/mo | Yes | 50 /mo | Yes | Yes |
| 16 | Arize Phoenix | 7.0 | Free plan | Free | Yes | — | Yes | Yes |
| 17 | Galileo | 7.0 | Free plan | $100/mo | Yes | 100 /mo | — | — |
| 18 | HoneyHive | 7.0 | Free plan | Free | Yes | — | Yes | Yes |
| 19 | Braintrust | 6.9 | Free plan | $249/mo | Yes | 249 /mo | — | — |
| 20 | Parea AI | 6.9 | Free plan | $150/mo | Yes | — | — | — |
| 21 | Confident AI | 6.8 | Free plan | $200/mo | Yes | 200 /mo | — | — |
| 22 | AgentOps | 6.6 | No | $40/mo | Yes | 40 /mo | Yes | — |
| 23 | Ragas | 6.6 | No | — | Yes | — | — | — |
| 24 | Lunary | 5.8 | No | — | No | — | Yes | Yes |
| 25 | OpenLLMetry | 5.7 | No | — | Yes | — | Yes | — |
Is your tool on this list?
Numbered spots on this list can be sponsored, and a sponsored row is labelled as paid.
Questions about this list
Which LLM observability tool is ranked first on Specifiction?
Evidently AI is ranked #1 of 26 with a score of 7.9. W&B Weave is second and Opik third.
How many of these have a free plan?
21 of the 25 on this page publish a free plan on their own pricing pages.
Which is the cheapest paid option?
On this page, Respan (formerly Keywords AI) has the lowest first paid tier we found: $16.58/mo.
How is this list ranked?
Ranked on what each maker publishes, the fullest spec sheet first: how deeply the product is documented, the platforms it runs on, a free tier or trial to test it, and its standing.
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