Category
LLM Observability
See what your LLM app is really doing.
21 tools·20 with free plan·11 with free trial
Read the editor's roundup →Trace, monitor, and evaluate LLM apps — logging, cost tracking, and quality evals (LLMOps).
21 tools reviewed20 with a free plan11 with a free trial21 with an API19 self-hostable
Where to start
Not enough community votes to rank this category yet — this is a shortlist, not an order of merit.
Open-source LLM and agent observability built on OpenTelemetry.
Phoenix is a strong, genuinely free way to get OpenTelemetry-based tracing and evaluation for LLM and agent apps, and self-hosting in one command lowers the barrier a lot. Two honest notes: the richer production features live in the paid Arize AX platform, and Arize agreed to be acquired by Dynatrace (~$915M) in August 2026, so watch how the open-source project's governance and roadmap evolve.
freemium·Free (OSS); Arize AX Pro from ~$50/mo
Observability, evaluation, and experimentation platform for LLM teams
A solid choice for teams that need to evaluate and monitor LLM apps in production, with prebuilt evals and dashboards. The caveat is that it assumes real engineering maturity and adds another layer to maintain, so it is overkill for hobby projects.
freemium·$0
Eval-first evaluation and observability platform for AI applications.
Braintrust is a serious, well-funded choice for teams that want to make evaluation systematic and wire it into CI/CD. The eval tooling, playground, and production-traces-to-dataset loop are genuinely strong. Trade-offs: it is not open source, self-hosting is Enterprise-only, and pricing jumps from free to $249 per month with many controls like SSO and RBAC behind Enterprise. Data- and score-based billing also makes costs less predictable at volume.
freemium·$249/mo
All LLM Observability
OpenTelemetry-native observability for LLM calls, tools, and agent handoffs
#opentelemetry#llm tracing#agent observability#token cost 4 views
Prompt management, versioning, and observability workspace for non-technical teams
#prompt-management#llm-observability#prompt-versioning#evaluation 1 views
Other AI tool categories
Frequently asked questions
- What's the best llm observability tool?
- Arize Phoenix currently leads in community votes. Phoenix is a strong, genuinely free way to get OpenTelemetry-based tracing and evaluation for LLM and agent apps, and self-hosting in one command lowers the barrier a lot. Two honest notes: the richer production features live in the paid Arize AX platform, and Arize agreed to be acquired by Dynatrace (~$915M) in August 2026, so watch how the open-source project's governance and roadmap evolve.
- Are there free options?
- 20 tools in this category offer a free plan. Another 11 have a free trial.
- How do you rank these tools?
- Tools are ranked by a combination of community upvotes, editorial review, and feature breadth. Our editors review pricing and capabilities quarterly.
- Can I suggest a tool we're missing?
- Yes — submit it here. Our team reviews submissions weekly.