Best LLM Observability Tools in 2026
Updated
In short: Arize AX is ranked #1 of 26 as of 4 October 2026, ahead of Evidently AI and Helicone. The best-ranked option with a free plan is Evidently AI. The lowest first paid tier on this page is Respan (formerly Keywords AI) at $16.58/mo.
When you need visibility into model behavior, observability tools can be compared by the signals and workflow details they list. Agent tracing, LLM tracing, and retrieval tracing help distinguish the kinds of activity represented; LLM evaluations and prompt management add other dimensions to consider. Token cost tracking, deployment options, free-plan availability, and paid starting prices round out the comparison. Arize AX is first among the entries shown, followed by Langfuse and Opik. W&B Weave, Arize Phoenix, LangSmith, Helicone, and LangWatch are also near the start. Match the listed tracing and evaluation features to the work you need to inspect, and consider which deployment and pricing terms 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.
Recognised 40% · Phone app 26% · Documented 20% · Free plan 14% of the score
- 1 Arize AX No phone app RecognisedPhone appDocumentedFree plan 6.4$50/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 2 Evidently AI No phone app RecognisedPhone appDocumentedFree plan 6.4$80/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 3 Helicone No phone app RecognisedPhone appDocumentedFree plan 6.4$79/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 4 Laminar No phone app RecognisedPhone appDocumentedFree plan 6.4$30/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 5 Langfuse No phone app RecognisedPhone appDocumentedFree plan 6.4$29/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 6 OpenLIT No phone app RecognisedPhone appDocumentedFree plan 6.4Free LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 7 Opik No phone app RecognisedPhone appDocumentedFree plan 6.4$19/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 8 Respan (formerly Keywords AI) No phone app RecognisedPhone appDocumentedFree plan 6.4$16.58/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 9 W&B Weave No phone app RecognisedPhone appDocumentedFree plan 6.4$60/mo LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 10 Braintrust No phone app RecognisedPhone appDocumentedFree plan 6.3$249/mo
- 11 Confident AI No phone app RecognisedPhone appDocumentedFree plan 6.3$200/mo
- 12 Galileo No phone app RecognisedPhone appDocumentedFree plan 6.3$100/mo
- 13 Giskard No phone app RecognisedPhone appDocumentedFree plan 6.3Free
- 14 Maxim AI No phone app RecognisedPhone appDocumentedFree plan 6.3$29/mo
- 15 Parea AI No phone app RecognisedPhone appDocumentedFree plan 6.3$150/mo
- 16 Promptfoo No phone app RecognisedPhone appDocumentedFree plan 6.3Free
- 17 Fiddler AI No phone app RecognisedPhone appDocumentedFree plan 5.5 LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 18 HoneyHive No phone app RecognisedPhone appDocumentedFree plan 5.5 LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 19 LangSmith No phone app RecognisedPhone appDocumentedFree plan 5.5 LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 20 LangWatch No phone app RecognisedPhone appDocumentedFree plan 5.5 LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 21 AgentOps No phone app RecognisedPhone appDocumentedFree plan 5.4 LLM tracing: Yes
- 22 Arize Phoenix No phone app RecognisedPhone appDocumentedFree plan 5.4 LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 23 OpenLLMetry No phone app RecognisedPhone appDocumentedFree plan 5.3 LLM tracing: Yes
- 24 Lunary No phone app RecognisedPhone appDocumentedFree plan 5.2 LLM tracing: YesLLM evaluations: YesPrompt management: Yes
- 25 Ragas No phone app RecognisedPhone appDocumentedFree plan 4.9
Is your app on this list?
Numbered spots on this list can be sponsored. They are labelled, and the editorial order and scores never change for payment.
Questions about this list
Which LLM observability tool is ranked first on Samsung Mobile US Press?
Arize AX is ranked #1 of 26 with a score of 6.4. Evidently AI is second and Helicone third.
How many of these have a free plan?
16 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 mobile-first: a phone app alongside the web or desktop product, a free tier and the depth of its documentation. Paid placements never change a rank.