Start by deciding whether the purchase must also solve model-provider routing. Then compare the work your team does to diagnose failures and release better prompts.
Teams deciding between Helicone and LangSmith
Helicone
Inspect its AI Gateway first if provider access and request operations are part of the purchase.
LangSmith
Inspect its tracing, evaluation, and prompt engineering flow if development iteration is the central requirement.
Lunary
Add it to the shortlist when the team needs a shared investigation around customer conversations and application runs.
At a glance
| Evaluation dimension | Helicone | LangSmith |
|---|---|---|
| Architecture starting point | AI Gateway and request operations | Application tracing and development workflow |
| Prompt work | Prompt management and gateway integration | Prompt engineering and evaluation |
| Data extraction | ETL tooling and REST API | SDK queries and bulk exports with eligibility |
| First proof | Provider failure plus complete application context | Trace diagnosis plus baseline/candidate comparison |
Compare equivalent layers
Helicone documents an AI Gateway with a common provider interface. LangSmith documents application tracing and an evaluation platform. These may enter the architecture at different points. Write down which capabilities must be replaced: provider access, request logging, custom spans, prompts, or experiments. Treat any serving-path change as its own engineering decision.
Reconstruct a failure across model and tools
Use an agent task where a provider succeeds but a later tool fails. A complete diagnosis must show the user request, model operation, actual tool outcome, and final response. Include custom instrumentation where necessary. Compare how easily a teammate discovers the failing step without knowing the implementation in advance.
Evaluate the prompt workflow you will use
Helicone documents prompt management and datasets. LangSmith documents prompt engineering and evaluation. In both, test one candidate prompt against a fixed baseline and inspect individual failures. Check that the version used in production can be related to the version being reviewed. Product category labels should not substitute for this practical check.
Budget the switch beyond the subscription
Helicone documents ETL routes for request data, including optional bodies. LangSmith documents SDK queries and eligible bulk exports. Validate what the archive contains and how you will map it to future datasets. Include routing changes, prompt retrieval, identity propagation, retention, and staff time in the migration estimate.
Agree on the unit of success
Gateway requests, traced operations, and user tasks are not interchangeable counts. A successful agent task may generate several model requests; a failed request may be retried within an ultimately successful task. Decide which identifiers connect those events and which outcome determines success. During the trial, reconcile one task manually from beginning to end. This gives you a sound basis for comparing costs and makes an apparent discrepancy between the products' charts easier to explain.
Common questions
Is Helicone only a proxy?
No. Its documentation also covers prompt management, datasets, custom logging, and data access. Evaluate the full capabilities relevant to your workload.
Do I need LangChain to use LangSmith?
No. LangSmith supports framework-independent tracing; verify the instrumentation for the framework and SDK versions you use.
Sources & methodology
Lunary publishes this guide. We compare documented workflows and explain where each approach fits; this is not an independent benchmark or a hands-on product rating. Features, limits, and commercial terms can change. Check the linked vendor documentation before deciding.