LangSmith vs PromptLayer
LangSmith
langchain.com
PromptLayer
promptlayer.comSide by side
| Figure | LangSmith | PromptLayer |
|---|---|---|
| Price from | $39/mo | $49/mo |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | — |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 3 | 4 |
| Spec score · Prompting Tool | 9.3 (#2) | 7.8 (#6) |
| Spec score · Llm Developer Tools | 9.0 (#3) | 7.6 (#13) |
| Spec score · AI LLM Observability Tools | 9.1 (#3) | 7.7 (#21) |
| Spec score · Prompt Engineering Tools | 9.1 (#4) | 7.8 (#17) |
| Evaluation | Evaluation supports offline datasets, online production evaluations, human annotation queues and side-by-side experiment comparison. | Evaluations can be triggered on new prompt versions, through the API, or ad hoc in the UI, and include historical backtests and side-by-side model comparisons. |
| Headquarters | San Francisco, California, United States | PromptLayer says it is located in New York City. |
| Hosting | The pricing page lists Cloud hosting for Developer and Plus, with Cloud, Hybrid, or Self-Hosted options for Enterprise. | Free, Pro, and Team are cloud-hosted in the US; Enterprise offers self-hosting on GCP, AWS, or Azure, EU cloud hosting, or cloud-hosted single tenancy. |
| Integrations | Documented integrations cover OpenAI, Anthropic, Bedrock, Gemini, Mistral, LiteLLM, OpenTelemetry, CrewAI, Vercel AI SDK, PydanticAI, AutoGen and many other frameworks and providers. | The LangChain integration exports traces through OpenTelemetry and supports cost and latency analytics, searchable metadata, and turning traces into evaluation datasets. |
| Observability | Its observability features include agent tracing, cost tracking, online LLM-as-judge and code evaluations, trajectory monitoring, and webhook or PagerDuty alerts. | PromptLayer tracks requests, traces, cost, latency, token usage, scores, and custom metadata, with OpenTelemetry span support. |
| Support | The Developer plan includes community support, and the Enterprise plan lists a support SLA. | The pricing comparison lists basic support for Free, Pro, and Team, and dedicated support for Enterprise. |
Plans
In their own words
LangSmith
LangSmith is a commercial agent-engineering platform for building, evaluating, deploying, monitoring, and improving AI agents. It supports offline evaluations on curated datasets and real-time scoring of production interactions. Evaluation methods include human review, heuristic checks, LLM-as-judge evaluators, pairwise comparisons, and custom Python or TypeScript evaluators. Annotation queues route runs to subject-matter experts for feedback that can calibrate evaluations, improve prompts, or augment datasets. The Playground compares prompt versions or model providers, and LangSmith chat can auto-improve prompts. Observability includes agent and retrieval tracing, token and general cost tracking, trajectory monitoring, online evaluations, and webhook or PagerDuty alerts. Traces can arrive through SDKs or an API from LangGraph, custom Python, or other stacks; SDKs are listed for Python, TypeScript, Go, and Java. Hosting ranges from cloud to hybrid and self-hosted Enterprise options. The Developer plan costs nothing, Plus costs $39 a month, and Enterprise pricing is custom.
PromptLayer
PromptLayer combines a prompt registry and visual prompt CMS with evaluations, observability, and agent tracing for teams building AI products. Teams can visually edit, version, test, and deploy prompts without waiting for an application redeploy, allowing domain experts and non-technical stakeholders to work alongside engineers. Evaluations can run when prompt versions change, through the API, or on demand in the UI. They include historical backtests and side-by-side model comparisons. Tracking covers requests, traces, cost, latency, token usage, scores, and custom metadata, with OpenTelemetry span support. The OpenAI integration includes versioned prompts, release labels, request observability, evaluations, and model comparisons. Free, Pro, and Team are cloud-hosted in the US; Enterprise offers self-hosting on GCP, AWS, or Azure, EU cloud hosting, or single-tenant cloud hosting. PromptLayer states that it maintains SOC 2 Type 2, HIPAA, GDPR, and CCPA compliance. Free costs nothing, Pro costs $49 a month, and Team costs $500 a month. Enterprise pricing is custom.