PromptLayer
Prompt version control, A/B testing, and analytics platform
Verdict
Excellent for non-engineers to trigger prompt experiments. Prompt registry with versioning is clean. Pairs well with LangChain. Limited eval depth compared to Langfuse.
Other Observability & Evals
- Arize AIStable
ML and LLM observability platform with drift detection and evaluation
- BraintrustExperimental
End-to-end LLM evaluation and experimentation platform
- HeliconeStable
LLM gateway with logging, caching, and cost analytics
- LangfuseProduction
Open-source LLM engineering platform — traces, evals, prompts
- OpenLLMetryExperimental
OpenTelemetry-based observability for LLMs
- Phoenix (Arize)Stable
Open-source AI observability with embedding and RAG tracing