Humanloop vs LangSmith (2026)
Updated March 10, 2026
Overview
Humanloop is a prompt engineering and evaluation platform that helps teams manage, version, and optimize LLM prompts. It provides prompt playgrounds, A/B testing, human feedback collection, and evaluation pipelines. Teams can track prompt performance across models and deploy optimized prompts to production.
LangSmith is LangChain's platform for tracing, evaluating, and deploying AI agents. Compare its features, pricing, pros and cons, and alternatives.
Key features
Core capabilities each platform advertises.
- Native tracing for LangChain and LangGraph
- OpenTelemetry and multi-language SDKs
- Offline and online evaluations
- Annotation queues and datasets
- Prompt Hub with versioning
Strengths and tradeoffs
What each tool does well, and the limitations to keep in mind.
Pros
- Collaborative platform for team development
- Version control for prompts
- A/B testing and evaluation tools
- Free tier for individuals
Cons
- Pro tier at USD 99/mo may be steep for small teams
- Learning curve for full feature utilization
- Requires commitment to platform workflow
Pros
- Native LangChain and LangGraph tracing with no extra instrumentation
- Evals, datasets, and annotation queues sit in the same workspace as traces
- Tracing, deployment, and sandboxes from one vendor
- Framework-agnostic SDKs and OpenTelemetry support
Cons
- Per-seat pricing on Plus, and the free plan allows one seat
- 14-day base retention, with longer retention billed at a higher rate
- LLM Gateway is still in beta
- Self-hosting and hybrid deployment are Enterprise only
Humanloop or LangSmith — which should you choose?
Choose Humanloop if you wantChoose if you want
Choose LangSmith if you wantChoose if you want
- Debugging LangChain and LangGraph agents
- Evaluating agent output against datasets
- Human review through annotation queues
- Deploying long-running agents
Compare Humanloop and LangSmith on your own traffic
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