Best LLM Observability Tools in 2026
Updated
In short: Evidently AI is ranked #1 of 26 as of 4 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 monitor an LLM application, you may want to see how requests move through models, agents and retrieval, as well as how prompts and evaluations are managed. Compared on agent tracing, LLM tracing and retrieval tracing, the tools also differ in LLM evaluations, prompt management and token cost tracking. Deployment options and plan details can help narrow the choices. Evidently AI, W&B Weave and Opik are among the listed tools. Compare their stated capabilities with the signals you need to follow, and weigh free-plan availability and paid-from pricing against your requirements.
26 LLM observability tools ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
LLM Observability Tools, ranked on how quickly a newcomer can get going. 18 of the 25 on this page can be tried for free.
- 1 Evidently AIPaid from $80/mo
- Free to practise on: yes
- Free trial: yes
- Well documented: yes
- Runs where you work: yes
- 2 W&B WeavePaid from $60/mo
- Free to practise on: yes
- Free trial: yes
- Well documented: yes
- Runs where you work: yes
- 3 OpikPaid from $19/mo
- Free to practise on: yes
- Free trial: yes
- Well documented: yes
- Runs where you work: not on record
- 4 HeliconePaid from $79/mo
- Free to practise on: yes
- Free trial: yes
- Well documented: yes
- Runs where you work: not on record
- 5 Respan (formerly Keywords AI)Paid from $16.58/mo
- Free to practise on: yes
- Free trial: yes
- Well documented: yes
- Runs where you work: not on record
- 6 Maxim AIPaid from $29/mo
- Free to practise on: yes
- Free trial: yes
- Well documented: yes
- Runs where you work: not on record
- 7 OpenLITFree plan
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: yes
- 8 PromptfooFree plan
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: yes
- 9 LangfusePaid from $29/mo
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 10 Arize AXPaid from $50/mo
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 11 GiskardFree plan
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 12 LaminarPaid from $30/mo
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 13 BraintrustPaid from $249/mo
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 14 GalileoPaid from $100/mo
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 15 Parea AIPaid from $150/mo
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 16 Confident AIPaid from $200/mo
- Free to practise on: yes
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 17 Ragas
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 18 LangWatchPaid from €29/mo
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 19 AgentOps
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 20 Arize Phoenix
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 21 Fiddler AI
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 22 HoneyHive
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 23 LangSmithPaid from $39/mo
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 24 Lunary
- Free to practise on: not on record
- Free trial: not on record
- Well documented: yes
- Runs where you work: not on record
- 25 OpenLLMetry
- Free to practise on: not on record
- Free trial: not on record
- Well documented: not on record
- Runs where you work: not on record
Compare all 25 in a table
| # | Platform | Score | Free plan | From | Free plan | Paid from | LLM tracing | LLM evaluations |
|---|---|---|---|---|---|---|---|---|
| 1 | Evidently AI | 8.0 | Free plan | $80/mo | Yes | — | Yes | Yes |
| 2 | W&B Weave | 8.0 | Free plan | $60/mo | Yes | 60 /mo | Yes | Yes |
| 3 | Opik | 7.8 | Free plan | $19/mo | Yes | 19 /mo | Yes | Yes |
| 4 | Helicone | 7.7 | Free plan | $79/mo | Yes | 79 /mo | Yes | Yes |
| 5 | Respan (formerly Keywords AI) | 7.7 | Free plan | $16.58/mo | Yes | 199 /mo | Yes | Yes |
| 6 | Maxim AI | 7.6 | Free plan | $29/mo | Yes | — | — | — |
| 7 | OpenLIT | 7.4 | Free plan | Free | Yes | — | Yes | Yes |
| 8 | Promptfoo | 7.3 | Free plan | Free | Yes | — | — | — |
| 9 | Langfuse | 7.2 | Free plan | $29/mo | Yes | 29 /mo | Yes | Yes |
| 10 | Arize AX | 7.1 | Free plan | $50/mo | Yes | 50 /mo | Yes | Yes |
| 11 | Giskard | 7.1 | Free plan | Free | Yes | — | — | — |
| 12 | Laminar | 7.1 | Free plan | $30/mo | Yes | 30 /mo | Yes | Yes |
| 13 | Braintrust | 7.0 | Free plan | $249/mo | Yes | 249 /mo | — | — |
| 14 | Galileo | 7.0 | Free plan | $100/mo | Yes | 100 /mo | — | — |
| 15 | Parea AI | 7.0 | Free plan | $150/mo | Yes | — | — | — |
| 16 | Confident AI | 6.8 | Free plan | $200/mo | Yes | 200 /mo | — | — |
| 17 | Ragas | 6.2 | No | — | Yes | — | — | — |
| 18 | LangWatch | 6.1 | Free plan | €29/mo | Yes | — | Yes | Yes |
| 19 | AgentOps | 6.0 | No | — | Yes | 40 /mo | Yes | — |
| 20 | Arize Phoenix | 6.0 | No | — | Yes | — | Yes | Yes |
| 21 | Fiddler AI | 6.0 | No | — | Yes | — | Yes | Yes |
| 22 | HoneyHive | 6.0 | No | — | Yes | — | Yes | Yes |
| 23 | LangSmith | 6.0 | Free plan | $39/mo | Yes | — | Yes | Yes |
| 24 | Lunary | 5.7 | No | — | No | — | Yes | Yes |
| 25 | OpenLLMetry | 5.7 | No | — | Yes | — | Yes | — |
Is your platform 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 The Geeks Club?
Evidently AI is ranked #1 of 26 with a score of 8.0. W&B Weave is second and Opik third.
How many of these have a free plan?
18 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 how quickly a newcomer can get going: documentation depth, a free tier or trial, and the platforms it runs on. Paid placements never change a rank.