Best AI LLM Observability Tools in 2026
Updated
In short: W&B Weave is ranked #1 of 23 as of 4 October 2026, ahead of OpenLIT and Opik. The best-ranked option with a free plan is OpenLIT. The lowest first paid tier on this page is Respan (formerly Keywords AI) at $16.58/mo.
AI LLM observability tools help you inspect and evaluate activity in applications that use large language models. Compare LLM trace capture and failure tracking for visibility into requests and problems, alongside latency metrics, output evaluations, and token cost tracking. Free-plan availability and retention, plus paid-from pricing, add practical points of comparison. The ranking opens with Arize AX, Opik, and W&B Weave, with Langfuse and Agenta among the next entries. Arize Phoenix, Braintrust, and Helicone are also shown near the top. Think about whether your priority is tracing, diagnosing failures, reviewing outputs, or monitoring latency and token costs, then use the listed criteria to compare options.
23 AI LLM observability tools ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
#1 W&B Weave Top pick · 7.3 Free plan · $60/mo
#2 OpenLIT Runner-up · 7.2 Free plan · Free
#3 Opik Also great · 7.1 Free plan · $19/mo
- Free planFree trial apiLinuxmacOSself-hostedWebWindows
- Free plan
- Yes
- Paid from
- 60 /mo
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms$60/mofirst paid tier About W&B WeaveVisit site - Free plan apiLinuxmacOSself-hostedWebWindows
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - Free planFree trial apiLinuxself-hostedWeb
- Free plan
- Yes
- Paid from
- 19 /mo
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms$19/mofirst paid tier About OpikVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 29 /mo
RecognisedDocumentedFree planPlatforms$29/mofirst paid tier About AgentaVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 49 /mo
- LLM trace capture
- Yes
- Token cost tracking
- Yes
- Output evaluations
- Yes
- Latency metrics
- Yes
RecognisedDocumentedFree planPlatforms$49/mofirst paid tier About PortkeyVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 249 /mo
RecognisedDocumentedFree planPlatforms$249/mofirst paid tier About BraintrustVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 200 /mo
RecognisedDocumentedFree planPlatforms$200/mofirst paid tier About Confident AIVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 100 /mo
RecognisedDocumentedFree planPlatforms$100/mofirst paid tier About GalileoVisit site - Free planFree trial apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 79 /mo
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms$79/mofirst paid tier About HeliconeVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 29 /mo
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms$29/mofirst paid tier About LangfuseVisit site - Free planFree trial apiself-hostedWeb
- Free plan
- Yes
RecognisedDocumentedFree planPlatforms$29/mofirst paid tier About Maxim AIVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 49 /mo
RecognisedDocumentedFree planPlatforms$49/mofirst paid tier About PromptLayerVisit site - Free planFree trial apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 199 /mo
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms$16.58/mofirst paid tier About Respan (formerly Keywords AI)Visit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Paid from
- 50 /mo
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms$50/mofirst paid tier About Arize AXVisit site - Free plan apiself-hostedWeb
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - WebLinux
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - Web
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - Web
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - Web
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - Web
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - Web
- Free plan
- No
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms -
- Free plan
- Yes
- Token cost tracking
- Yes
RecognisedDocumentedFree planPlatforms - RecognisedDocumentedFree planPlatforms
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 AI LLM observability tool is ranked first on Everything Xiaomi?
W&B Weave is ranked #1 of 23 with a score of 7.3. OpenLIT is second and Opik third.
How many of these have a free plan?
15 of the 23 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: documentation depth, a free tier and the platforms it runs on. Paid placements never change a rank.