PromptLayer
Keep prompt revisions and evaluation datasets together when several people need to compare changes before rollout.
- Starting price
- Pro USD 49/month
- Free access
- 2,500 requests; 250 eval cells
- Billing unit
- Requests and execution transactions
- Platform
- Cloud prompt workspace
- Verified
- 26 Oct 2026
Overview
What you provide
- Provide versioned prompts, application request records and test examples with desired responses.
What you get
- The workspace records prompt changes and evaluation results that teams can compare across versions.
Choosing this tool
PromptLayer Pro mainly removes workspace and playground constraints; it does not multiply the included request allowance. Choose it when prompt iteration and collaboration are the bottleneck. Braintrust emphasizes traces, datasets and scores; LangSmith is a better comparison when agent deployment and observability are part of the same purchase.
A decision worked through
If a Pro workload produces 10,000 billable request transactions against 2,500 included requests, request overage alone is 7,500 × USD 0.003 = USD 22.50, for USD 71.50 including the platform fee. Agent-node and evaluation-cell transactions can add charges, and provider inference is outside this example.
PromptLayer alternatives for prompt versioning and evaluations
Compare PromptLayer with Braintrust, LangSmith for prompt versioning and evaluations. Compare the published operating scope as well as the billing unit.
| Product | Price / unit | Free allowance | Input → output | Key limit |
|---|---|---|---|---|
| PromptLayerRead profileOfficial source ↗ | Pro USD 49/mo plus transactions | Five users; one workspace | Prompts become versioned tests. | Pro keeps 2,500 included requests. |
| BraintrustRead profileOfficial source ↗ | Pro USD 249/mo plus usage | 1 GB; 10k scores monthly | Traces become scored experiments. | Starter retention is 14 days. |
| LangSmithRead profileOfficial source ↗ | Plus USD 39/seat/mo plus usage | 5k base traces and one seat | Agent runs become inspected traces. | Plus includes 10k traces total. |
Setup & workflow
- Register the prompt and its current release version.
- Compare the proposed revision on a fixed dataset.
- Keep the accepted version and its evaluation evidence together.
Requirements & installation
- Prepare a prompt registry and sanitize recorded requests before connecting production traffic.
Limits & review
- Additional usage can include requests, agent runs and evaluation cells. Free and Pro are hosted in the US; enterprise deployment options require separate agreement. A platform subscription does not establish a model-provider spending cap.
Your part
- Review dataset representativeness and require a human decision before promoting a prompt that changes production behavior.
Sources & verification5
This profile is based on official sources, not a hands-on product test.
Vendor descriptions and demos document advertised features. Editorial guidance is based on these sources.
- PromptLayer official pricingpromptlayer.com
- PromptLayer official productpromptlayer.com
- PromptLayer official referencepromptlayer.com
- Braintrust official referencebraintrust.dev
- LangSmith official referencewww.langchain.com
