Best LLM Observability Tools in 2026
Updated
As language-model applications grow more involved, visibility into their runs, prompts, and costs can matter. Compared on agent tracing, LLM tracing, and retrieval tracing, these tools also specify LLM evaluations, prompt management, and token cost tracking. Deployment options help you consider how a tool may fit your environment; free-plan availability and paid-from pricing add cost context. Arize AX, Evidently AI, and Helicone are among the named options, alongside Langfuse. Consider which parts of model behavior and application flow you need to inspect, then use the listed tracing and evaluation capabilities to compare potential fits.
LLM Observability Tools, one module each.A lit port is something its maker publishes; 25 of 25 with a known API signal have a public API.
- 01 Arize AX API yesFREE yesDOCS 7.4$50/mo
- 02 Evidently AI API yesFREE yesDOCS 7.4$80/mo
- 03 Fiddler AI API yesFREE yesDOCS 7.4Free
- 04 Helicone API yesFREE yesDOCS 7.4$79/mo
- 05 Laminar API yesFREE yesDOCS 7.4$30/mo
- 06 Langfuse API yesFREE yesDOCS 7.4$29/mo
- 07 LangSmith API yesFREE yesDOCS 7.4$39/mo
- 08 LangWatch API yesFREE yesDOCS 7.4€29/mo
- 09 Opik API yesFREE yesDOCS 7.4$19/mo
- 10 Respan (formerly Keywords AI) API yesFREE yesDOCS 7.4$16.58/mo
- 11 W&B Weave API yesFREE yesDOCS 7.4$60/mo
- 12 Arize Phoenix API yesFREE yesDOCS 7.3Free
- 13 Braintrust API yesFREE yesDOCS 7.3$249/mo
- 14 Confident AI API yesFREE yesDOCS 7.3$200/mo
- 15 Galileo API yesFREE yesDOCS 7.3$100/mo
- 16 Giskard API yesFREE yesDOCS 7.3Free
- 17 HoneyHive API yesFREE yesDOCS 7.3Free
- 18 Maxim AI API yesFREE yesDOCS 7.3$29/mo
- 19 OpenLIT API yesFREE yesDOCS 7.3Free
- 20 OpenLLMetry API yesFREE yesDOCS 7.3Free
- 21 Parea AI API yesFREE yesDOCS 7.3$150/mo
- 22 Promptfoo API yesFREE yesDOCS 7.3Free
- 23 TruLens API yesFREE yesDOCS 7.2Free
- 24 AgentOps API yesDOCS 7.0$40/mo
- 25 Lunary API yesDOCS 6.9$20/mo
Compare all 25 in a table
| # | Platform | Score | Free plan | From | Free plan | Paid from | LLM tracing | LLM evaluations |
|---|---|---|---|---|---|---|---|---|
| 1 | Arize AX | 7.4 | Free plan | $50/mo | Yes | 50 /mo | Yes | Yes |
| 2 | Evidently AI | 7.4 | Free plan | $80/mo | Yes | Yes | Yes | |
| 3 | Fiddler AI | 7.4 | Free plan | Free | Yes | Yes | Yes | |
| 4 | Helicone | 7.4 | Free plan | $79/mo | Yes | 79 /mo | Yes | Yes |
| 5 | Laminar | 7.4 | Free plan | $30/mo | Yes | 30 /mo | Yes | Yes |
| 6 | Langfuse | 7.4 | Free plan | $29/mo | Yes | 29 /mo | Yes | Yes |
| 7 | LangSmith | 7.4 | Free plan | $39/mo | Yes | Yes | Yes | |
| 8 | LangWatch | 7.4 | Free plan | €29/mo | Yes | Yes | Yes | |
| 9 | Opik | 7.4 | Free plan | $19/mo | Yes | 19 /mo | Yes | Yes |
| 10 | Respan (formerly Keywords AI) | 7.4 | Free plan | $16.58/mo | Yes | 199 /mo | Yes | Yes |
| 11 | W&B Weave | 7.4 | Free plan | $60/mo | Yes | 60 /mo | Yes | Yes |
| 12 | Arize Phoenix | 7.3 | Free plan | Free | Yes | Yes | Yes | |
| 13 | Braintrust | 7.3 | Free plan | $249/mo | Yes | 249 /mo | ||
| 14 | Confident AI | 7.3 | Free plan | $200/mo | Yes | 200 /mo | ||
| 15 | Galileo | 7.3 | Free plan | $100/mo | Yes | 100 /mo | ||
| 16 | Giskard | 7.3 | Free plan | Free | Yes | |||
| 17 | HoneyHive | 7.3 | Free plan | Free | Yes | Yes | Yes | |
| 18 | Maxim AI | 7.3 | Free plan | $29/mo | Yes | |||
| 19 | OpenLIT | 7.3 | Free plan | Free | Yes | Yes | Yes | |
| 20 | OpenLLMetry | 7.3 | Free plan | Free | Yes | Yes | ||
| 21 | Parea AI | 7.3 | Free plan | $150/mo | Yes | |||
| 22 | Promptfoo | 7.3 | Free plan | Free | Yes | |||
| 23 | TruLens | 7.2 | Free plan | Free | ||||
| 24 | AgentOps | 7.0 | $40/mo | Yes | 40 /mo | Yes | ||
| 25 | Lunary | 6.9 | $20/mo | No | Yes | Yes |
Is your platform on this list?
Numbered spots on this list can be sponsored, and a sponsored row is labelled as paid.