What is Respan and who is it for?

Respan is a YC-backed LLM observability and operations platform designed for teams shipping production LLM features. It provides a unified gateway, tracing, evals, and prompt versioning to replace ad-hoc logging setups.

Does Respan support multiple AI models?

Yes, Respan acts as a unified gateway routing to over 500 models from providers like OpenAI and Anthropic. It includes built-in fallback and error handling for these models.

Is Respan open source or self-hostable?

No, Respan is not open source. Self-hosting is not available unless you negotiate a specific enterprise arrangement with the company.

What SDKs and frameworks does Respan integrate with?

Respan provides SDKs for Python and TypeScript. It offers first-party integrations for LangChain, LlamaIndex, the Vercel AI SDK, and over 40 other frameworks.

Respan (formerly Keywords AI)

LLM engineering platform combining a multi-model gateway with tracing, evals, and prompt management.

Freemium· Free tier; paid plans (pricing not public); enterprise on requestEvaluationMulti-model (500+ via gateway)7.1 / 10

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In short

Respan is an LLM engineering platform that combines a multi-model gateway with observability, evaluation, and prompt management tools. It is best for production teams seeking a unified vendor for routing, tracing, and quality regression testing.

Best for

Pick Respan if you're shipping a production LLM app and want one vendor for gateway routing, tracing, evals, and prompt versioning.

Skip if

Skip it if you need a self-hostable open-source observability stack or you're happy stitching together Langfuse, Helicone, and your own dashboards.

Respan, previously branded as Keywords AI, is a YC-backed LLM observability and operations platform. It sits in front of your AI app as a unified gateway routing to 500+ models from OpenAI, Anthropic, and others with built-in fallback and error handling, while logging every call for tracing, cost, latency, and error analysis. On top of that runtime data, it layers an evaluation system that mixes rule-based checks, AI judges, and human review into repeatable workflows.

The platform is aimed at teams shipping production LLM features who have outgrown ad-hoc logging and want a single pane for monitoring, prompt versioning, and quality regression testing. It claims to have processed 80 trillion+ tokens across customers, which puts it in the same competitive bracket as LangSmith, Helicone, and Langfuse. There's a free tier and paid plans, with enterprise demos available on request.

SDKs ship for Python and TypeScript, with first-party integrations for LangChain, LlamaIndex, the Vercel AI SDK, and 40+ other frameworks. Not open source, so self-hosting is off the table unless you negotiate an enterprise arrangement.

Editor's take

A credible LangSmith competitor that doubles as a model gateway, which is a genuinely useful combo if you're tired of running observability and routing as separate systems. The rebrand from Keywords AI to Respan is recent enough that some docs and case studies still reference the old name — worth checking pricing and SDK stability before committing.

— The AI Tool Bible editorial team

Pros

✅ Unified gateway to 500+ models with fallback and error handling
✅ End-to-end loop: trace, evaluate, monitor, version prompts in one UI
✅ Eval system mixes rules, AI judges, and human review
✅ Broad SDK and framework coverage (LangChain, LlamaIndex, Vercel AI SDK)
✅ YC-backed with serious production scale (80T+ tokens claimed)

Cons

⚠️ Closed source — no self-host option for most customers
⚠️ Paid pricing not transparent on the site
⚠️ Recent rebrand from Keywords AI may cause doc and link churn
⚠️ Gateway dependency adds a network hop and vendor lock-in

Use cases

llm-observabilityprompt-managementmodel-routingevalsproduction-monitoring

Frequently asked

What is Respan and who is it for?: Respan is a YC-backed LLM observability and operations platform designed for teams shipping production LLM features. It provides a unified gateway, tracing, evals, and prompt versioning to replace ad-hoc logging setups.
Does Respan support multiple AI models?: Yes, Respan acts as a unified gateway routing to over 500 models from providers like OpenAI and Anthropic. It includes built-in fallback and error handling for these models.
Is Respan open source or self-hostable?: No, Respan is not open source. Self-hosting is not available unless you negotiate a specific enterprise arrangement with the company.
What SDKs and frameworks does Respan integrate with?: Respan provides SDKs for Python and TypeScript. It offers first-party integrations for LangChain, LlamaIndex, the Vercel AI SDK, and over 40 other frameworks.
How does Respan handle evaluations?: The platform features an evaluation system that mixes rule-based checks, AI judges, and human review into repeatable workflows. This allows for quality regression testing alongside runtime monitoring.