PromptLayer

Free tier

The collaboration layer for AI engineering teams — prompt CMS, eval harness, and observability stack

Free tier available·All audiences·API available

Key strengths

Prompt version control and CMS for managing prompt templatesEvaluation harness for testing and comparing LLM outputsFull observability stack for tracking LLM requests and performanceEnables non-engineers (domain experts) to iterate on prompts without code changesPurpose-built for AI engineering team collaboration

Free tier + paid plans

San Francisco, USA

Founded 2022

Get alerts when PromptLayer changes

Free. We'll email you when pricing, the free tier, API access or open-source status changes.

No ratings yet

PromptLayer is an AI engineering platform that provides a prompt CMS, evaluation harness, and observability stack for teams building LLM-powered applications. It sits as a middleware layer between your application and LLM providers, logging all requests and responses, enabling prompt versioning and A/B testing, and surfacing performance metrics. Engineers integrate via a lightweight SDK or API proxy, while non-technical collaborators interact through the visual dashboard to iterate on prompts and review evals.

Alternatives

Alternatives to PromptLayer

See all alternatives

Phoenix

Free

AI observability

The open-source platform for AI agent development, tracing, and evaluation

Free OSS with paid Cloud instances available

LlamaIndexOpenTelemetryDockerKubernetes

Free tierDevAPIOSSSelf-host

Vendor Agnostic9.0kPopular

Opik

Free

AI observability

Open-source AI observability & evaluation platform for the agentic era

Free tier available, enterprise versions for teams

ClaudeGitHubMCP

Free tierDevAPIOSSSelf-host

19kGrowing

Traceloop

Free

AI observability

LLM reliability platform that turns evals and monitors into a continuous feedback loop

Free tier available · enterprise plans

OpenAIAnthropicGeminiBedrock+2

Free tierDevAPIOSSSelf-host

Agnostic (OpenAI, Anthropic, Gemini, Bedrock, Ollama, and 20+ others)Growing

AgentOps

Free

AI observability

Trace, Debug, & Deploy Reliable AI Agents — the leading developer platform for AI agents and LLM apps.

Free · Basic $0/mo · Pro $40+/mo · Enterprise custom

OpenAICrewAIAutogen

Free tierDevAPISelf-host

Growing

Langfuse

Free

AI observability

Open-source AI engineering platform to debug, monitor, and improve LLM applications and agents

Hobby (free): 50k units/month, 30 days data access, 2 users. Core: $29/month, 100k units/month included, 90 days data access, unlimited users. Pro: $199/month, 100k units/month included, 3 years data access, high rate limits, SOC2 & ISO27001. Enterprise: $2,499/month. Additional usage: $8/100k units.

OpenAILangChainAnthropicAzure+1

Free tierDevAPIOSSSelf-host

35kPopular

Braintrust

Free

AI observability

The AI observability platform for building quality AI products at scale

Flexible pricing plans for teams of all sizes

PythonTypeScriptGoRuby+1

Free tierEveryoneAPISelf-host

Browse all 14 ai observability tools

Is PromptLayer yours? Claim the listing & get the badge