LangSmith alternative for tracing and evals

If you’re looking for LangSmith alternatives for tracing and evals, here are the main options depending on what you need:

Strong alternatives

• OpenTelemetry + Grafana/Tempo/Loki

  • Best if you want vendor-neutral tracing and full observability control.
  • Good for distributed traces, logs, metrics, and can be adapted for LLM apps.
  • Evals usually need to be built separately or integrated via custom pipelines.

• Arize Phoenix

  • One of the best open-source options for LLM tracing, debugging, and evals.
  • Supports prompt/response inspection, embeddings, drift, retrieval analysis, and evaluation workflows.
  • Good fit if you want something closer to LangSmith’s LLM-focused experience.

• Weights & Biases Weave

  • Good for LLM tracing, experiment tracking, and evals.
  • Especially useful if you already use W&B for ML experiments.
  • Better for teams doing systematic experimentation and comparison.

• Helicone

  • Focused on LLM observability and usage analytics.
  • Great for tracing, request logs, cost tracking, latency, and prompt monitoring.
  • Evals are more limited than LangSmith/Phoenix, but still useful.

• Traceloop

  • Open-source tracing for LLM apps built around OpenTelemetry.
  • Good if you want tracing with a more standards-based approach.
  • Evals are less mature than some dedicated tools.

• Braintrust

  • Strong for evals, prompt testing, and experiment management.
  • Offers datasets, scoring, comparison, and tracing features.
  • Good if your main pain point is evaluation rather than pure observability.

If you want the closest match to LangSmith

1. Arize Phoenix — best open-source LLM tracing + evals
2. Braintrust — best for eval workflows and prompt experimentation
3. Weave — good for tracing + experiment tracking

Quick decision guide

• Need open-source and LLM-native tracing/evals? → Phoenix
• Need enterprise eval workflows and prompt versioning? → Braintrust
• Need standard observability stack integration? → OpenTelemetry
• Need cost/latency/request monitoring for LLM APIs? → Helicone
• Already use W&B? → Weave

If you want, I can also give you:

• a feature comparison table
• open-source only alternatives
• or recommendations based on your stack, like Python / JS / LangChain / LlamaIndex / OpenAI / Anthropic.