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Software · head to head

LangSmith vs PromptLayer

L

LangSmith

Software

Know what your agents are really doing

From
On request
Rated
-
Full reviewWebsite
PromptLayer logo

PromptLayer

Software

Collaboration platform for prompt management, evaluation, and observability

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only PromptLayer has a free tier, so it costs nothing to try first.
  • Each has a real cost: LangSmith usage beyond the included trace allotment is billed in LangChain Compute Units at $1.50 per LCU and Storage Units at $1.00 per LSU, an unfamiliar metering unit compared to flat per-seat pricing, as of August 2026.; PromptLayer the free plan is capped at only 2,500 requests per month, quite limited for active production use.

Where they differ

Only the attributes on which LangSmith and PromptLayer actually diverge.

Attributes where LangSmith and PromptLayer differ
AttributeLangSmithPromptLayer
Starting priceOn requestFree
Pricing modelsubscriptionfreemium
Free tierNoYes
PlatformsWebweb, api

Identical on both: user rating (Not yet rated), category (Unknown).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in LangSmith

Nothing recorded that PromptLayer does not also cover.

Only in PromptLayer

  • Visual prompt management
  • Agent observability
  • Evaluations
  • Version control
  • Cost and latency monitoring
  • Agent workflow tracing

What people use each for

The jobs each tool is most often brought in to do.

LangSmith

No use cases recorded yet. See the LangSmith review.

PromptLayer

  • Versioning and deploying prompts without code redeploysnot LangSmith
  • Running evaluations with human review before production releasenot LangSmith
  • Tracing multi-step agent workflows for debuggingnot LangSmith
  • Monitoring LLM cost and latency by featurenot LangSmith

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

LangSmith

  • Usage beyond the included trace allotment is billed in LangChain Compute Units at $1.50 per LCU and Storage Units at $1.00 per LSU, an unfamiliar metering unit compared to flat per-seat pricing, as of August 2026.

PromptLayer

  • The free plan is capped at only 2,500 requests per month, quite limited for active production use.
  • The Team plan jumps to $500/month, a large step up from the $49/month Pro plan.
  • Overage transaction fees apply on top of subscription costs, which can make total spend less predictable.
  • Enterprise-grade features like HIPAA BAAs and custom deployment require contacting sales.

Pricing, plan by plan

LangSmith

On request

No published plan breakdown. See the LangSmith review.

PromptLayer

Free
  • FreeFree
    • 5 users
    • 2,500 requests/month
    • 1 workspace
  • Pro$49/month
    • Unlimited playgrounds and workspaces
    • 150MB datasets
    • Pay-as-you-go overage at $0.003/transaction
  • Team$500/month
    • 25 users
    • 100k+ monthly requests
    • Webhooks
  • Enterprise$undefined/mo
    • Custom limits
    • Role-based access controls
    • HIPAA with BAA

Which should you pick?

Choose LangSmith if

Nothing in the data separates LangSmith from PromptLayer on the points above - pick on price and on how each one feels to use.

LangSmith review

Choose PromptLayer if

  • You need visual prompt management.
  • You want to start without paying.
  • You work on web, api.
  • You also want agent observability.
PromptLayer review

Questions people ask

Is LangSmith or PromptLayer better?
Neither clearly leads. LangSmith starts at On request and PromptLayer at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, LangSmith or PromptLayer?
PromptLayer has a free tier; the other does not. Paid plans start at On request for LangSmith and Free for PromptLayer.
Does LangSmith or PromptLayer run on more platforms?
LangSmith runs on Web. PromptLayer runs on web, api.
Can I use PromptLayer for free?
Yes. PromptLayer has a free tier, so you can try it without paying. LangSmith starts at On request.
What can LangSmith do that PromptLayer cannot?
PromptLayer covers Visual prompt management, Agent observability, Evaluations, Version control.

Answered from the vendors’ own pages

PromptLayer: What does PromptLayer cost?

PromptLayer has a free plan, a Pro plan at $49/month, a Team plan at $500/month, and custom Enterprise pricing, with additional usage billed per transaction beyond plan limits.

Source
PromptLayer: Is there a free plan, and what are its limits?

The Free plan includes 5 users, 2,500 requests per month, 1 workspace, 250 monthly eval cell executions, and datasets up to 10MB.

Source
PromptLayer: How is usage metered beyond the plan limits?

Additional usage is charged per transaction for requests, agent runs, and evaluation cell runs, at $0.003/transaction on Pro and $0.002/transaction on Team.

Source
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