Directory · Observability
Braintrust
AI evaluation and observability platform — traces feed directly into eval datasets, regression tests, and prompt experiments.
Freemium
Best for
Eval-first teams, prompt A/B testing, quality loops tied to production traces
Pros and cons
Pros
- Traces to evals in one product
- Strong experiment and scoring UX
- Good for PM + eng collaboration
Cons
- Not self-hostable (managed only)
- Pricier at scale than OSS Langfuse
- Less infra-flexible than OpenTelemetry
Alternatives
More observability tools
Langfuse
Observability
Open-source LLM observability — traces, evals, prompt versioning, and cost dashboards for production AI apps.
Best for
Debugging agent runs, tracking prompt changes, eval datasets, team visibility
Pros
- Self-hostable with generous OSS tier
- Traces tie prompts to outputs and cost
- Eval and dataset workflows built in
Cons
- Self-host needs Postgres + ClickHouse appetite
- Competes with a crowded observability market
- Instrumentation takes engineering time upfront
Alternatives
BraintrustPhoenix (Arize)LangSmith
Phoenix (Arize)
Observability
Open-source LLM tracing and evaluation from Arize — inspect spans, embeddings, and retrieval quality locally.
Best for
RAG debugging, embedding drift analysis, OSS tracing without vendor lock-in
Pros
- Free and open source
- Strong RAG and retrieval visualization
- Pairs with Arize cloud for production scale
Cons
- Smaller community than Langfuse
- Eval story less mature than Braintrust
- Self-host setup takes effort
Alternatives
LangfuseBraintrustLangSmith