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AI · head to head

PromptLayer vs Ray

PromptLayer logo

PromptLayer

AI

Collaboration platform for prompt management, evaluation, and observability

From
Free
Free plan
Yes
Full reviewWebsite
Ray logo

Ray

Machine Learning

Scale AI and Python applications

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: PromptLayer the free plan is capped at only 2,500 requests per month, quite limited for active production use.; Ray windows support is beta and multi node Ray clusters are untested on Windows
  • They diverge on capability: PromptLayer covers Visual prompt management, Ray covers Distributed computing.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which PromptLayer and Ray actually diverge.

Attributes where PromptLayer and Ray differ
AttributePromptLayerRay
Platformsweb, apiLinux, Mac, Windows
CategoryAIMachine Learning
FoundedUnknown2019

Identical on both: starting price (Free), pricing model (freemium), free tier (Yes), user rating (Not yet rated).

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 PromptLayer

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

Only in Ray

  • Distributed computing
  • Ray Train
  • Ray Tune
  • RLlib
  • Ray Serve
  • PyTorch
  • TensorFlow
  • Hugging Face

What people use each for

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

PromptLayer

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

Ray

  • Distributed AI model training and servingnot PromptLayer
  • Large-scale data processingnot PromptLayer
  • Reinforcement learning workloadsnot PromptLayer
  • ML inference servingnot PromptLayer

Where each one falls short

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

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.

Ray

  • Windows support is beta and multi node Ray clusters are untested on Windows
  • Windows lacks copy on write forking, which raises memory requirements, and Ray code assumes UNIX filenames
  • Multi node clusters are untested on Apple Silicon Macs
  • The Java API is experimental and community supported only, and requires matching Java and Python versions
  • Python 3.13 support is beta

Pricing, plan by plan

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

Ray

Free
  • Open SourceFree
    • Full Ray framework
    • All libraries
    • Community support
  • Anyscale PlatformFree
    • Managed infrastructure
    • Enterprise support
    • SLAs

Which should you pick?

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

Choose Ray if

  • You need distributed computing.
  • You want to start without paying.
  • You work on Linux, Mac, Windows.
  • You also want ray train.
Ray review

Questions people ask

Is PromptLayer or Ray better?
Neither clearly leads. PromptLayer starts at Free and Ray at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, PromptLayer or Ray?
PromptLayer starts at Free and Ray at Free.
Does PromptLayer or Ray run on more platforms?
PromptLayer runs on web, api. Ray runs on Linux, Mac, Windows.
Can I use PromptLayer for free?
Both have a free tier, so you can try either at no cost before committing.
What is PromptLayer best used for?
PromptLayer is most often used for versioning and deploying prompts without code redeploys, running evaluations with human review before production release, tracing multi-step agent workflows for debugging, monitoring llm cost and latency by feature. Of those, versioning and deploying prompts without code redeploys and running evaluations with human review before production release are not what Ray is typically brought in for.
What can PromptLayer do that Ray cannot?
PromptLayer covers Visual prompt management, Agent observability, Evaluations, Version control. Ray covers Distributed computing, Ray Train, Ray Tune, RLlib.

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
Ray: Is Ray free?

Yes. Ray is free and open source software with over 34,800 GitHub stars and 1,000+ contributors. Users can download and use the Ray framework at no cost.

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
Ray: Is there a paid option for Ray?

Yes. Anyscale, the managed platform built by Ray's creators, offers paid tiers with enterprise features like governance and advanced tooling. Specific Anyscale pricing details are not listed on the Ray website.

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
Ray: Can I try Ray with credits?

Yes. New users can try Ray with $100 credit on Anyscale's managed platform to explore the service.

Source
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