LangSmith vs Opik
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
AI tool · Freemium
LangChain's platform for tracing, evaluating and monitoring LLM apps, with a prompt hub and playground.
AI tool · Open source
Comet's open-source platform for logging, evaluating and monitoring LLM apps, including prompt optimisation.
The short answer
Choose LangSmith if you need…
- LangChain and LangGraph users
- Dataset-based evaluation
Choose Opik if you need…
- Open-source tracing and evals
- Automated prompt optimisation
Side-by-side
| LangSmith | Opik | |
|---|---|---|
| Type | Prompting · Evaluation & observability | Prompting · Evaluation & observability |
| Price | Freemium | Open source |
| Platforms | Web, API | Web, Self-hosted, API |
| Works with | LangChain, OpenAI | LangChain, OpenAI |
| Hands-on tested by us | Not yet | Not yet |
| Last checked | 2026-10-29 | 2026-10-29 |
What each one is
LangSmith
LangChain's platform for tracing, evaluating and monitoring LLM apps, with a prompt hub and playground. Deep tooling, especially inside the LangChain ecosystem. Less compelling if you don't use LangChain.
Opik
Comet's open-source platform for logging, evaluating and monitoring LLM apps, including prompt optimisation. Generous open-source feature set. Younger than some rivals, so expect rough edges.
Best for
LangSmith
- LangChain and LangGraph users
- Dataset-based evaluation
Opik
- Open-source tracing and evals
- Automated prompt optimisation
Strengths
LangSmith
- Detailed run traces
- Datasets and evaluators
- Prompt hub and playground
- Production monitoring
Opik
- Tracing and logging
- LLM-as-judge metrics
- Prompt library
- Agent optimiser
Frequently asked questions
What is the difference between LangSmith and Opik?
LangSmith: LangChain's platform for tracing, evaluating and monitoring LLM apps, with a prompt hub and playground. Opik: Comet's open-source platform for logging, evaluating and monitoring LLM apps, including prompt optimisation. LangSmith suits langchain and langgraph users, while Opik suits open-source tracing and evals.
Are LangSmith and Opik free?
LangSmith: Freemium. Opik: Open source.
What are other alternatives to LangSmith and Opik?
Other options people compare them with include Langfuse, Arize Phoenix, promptfoo, Braintrust, Confident AI (DeepEval).
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.