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PerUnit vs LangSmith

LLM development and debugging

LangSmith is LangChain's platform for building and debugging LLM applications. It's built for developers: prompt versioning, chain tracing, evaluation datasets. PerUnit is built for business decisions: cost per customer, margin by tier, and whether your AI features are net profitable.

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Feature comparison

CapabilityPerUnitLangSmith
Cost per customer
Cost by pricing tier (Free / Pro / Enterprise)
Cost by AI feature
Revenue vs. AI cost margin (Stripe integration)
Prompt and chain tracing
Dataset evaluation and regression testing
Works with non-LangChain stacks
Direct AI provider API sync (no pipelines)
No data engineering team required
SupportedPartialNot available

When LangSmith is a better fit

  • You're building with LangChain and need trace-level debugging
  • You're running A/B tests on prompts or chains
  • You need evaluation datasets and regression testing
  • You're iterating on RAG pipelines or agent workflows

When PerUnit is a better fit

  • You need cost attribution by customer, not by trace
  • You're a founder or PM making pricing decisions
  • You want to see AI spend vs revenue per account
  • You use OpenAI/Anthropic directly (no LangChain required)

Need cost attribution, not just totals?

PerUnit breaks down your AI spend by customer, feature, and pricing tier — and connects it to revenue. $199 $99/mo early access.

Get early access to PerUnit