What is the primary function of Kiln AI?

Kiln AI is a desktop workbench and open-source Python library that bundles RAG, tools, sub-agents, LLM-as-judge evals, synthetic data generation, and fine-tuning into a single local environment.

Which AI models does Kiln AI support?

It supports over 190 models across providers including OpenAI, Anthropic, Gemini, Ollama, Bedrock, and Azure OpenAI, preventing vendor lock-in.

How does Kiln AI handle data storage and collaboration?

The desktop app runs locally on macOS, Windows, and Linux, with datasets versioned in Git. This allows engineers, data scientists, and PMs to collaborate without SaaS lock-in.

What are the pricing options for Kiln AI?

Kiln AI offers a free Individual tier with rate-limited Pro features, a Team tier requiring access requests, and an Enterprise tier with custom pricing, SSO/SAML, and SLAs.

Kiln AI

Open-source workbench for building, evaluating, and fine-tuning AI agents across 190+ models.

Freemium· Free Individual tier; Team (request access); Enterprise (custom)EvaluationMulti-model7.2 / 10

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In short

Kiln AI provides a desktop workbench and Python library to build, evaluate, and fine-tune AI agents locally. It supports 190+ models and uses Git for dataset versioning, offering a local-first alternative to hosted platforms.

Best for

Pick Kiln AI if you want a local-first, Git-friendly workbench to evaluate and fine-tune LLM agents without piping prompts and datasets into a SaaS.

Skip if

Skip it if you want a fully-hosted, browser-based eval platform for non-technical teammates who won't install a desktop app.

Kiln AI is a desktop workbench plus open-source Python library for teams building production AI systems. It bundles the loop you'd otherwise stitch together yourself: RAG, tools/MCP, sub-agents, LLM-as-judge evals with golden datasets, synthetic data generation, prompt and agent auto-optimization, and fine-tuning. The desktop app runs locally on macOS, Windows, and Linux, with datasets versioned in Git so engineers, data scientists, and PMs can collaborate on the same eval set without a SaaS lock-in.

What sets Kiln apart is the split between a genuinely free, MIT-licensed Python library (4,500+ GitHub stars) for production deployment and a paid Kiln Pro layer that adds an AI assistant, auto-generated evals, and optimization. It supports 190+ models across OpenAI, Anthropic, Gemini, Ollama, Bedrock, and Azure OpenAI, so you're not locked to one provider. The Individual tier is free with rate-limited Pro features; Team is request-access with higher limits and email support; Enterprise adds SSO/SAML, SLAs, and a solutions engineer.

It's best thought of as a serious alternative to hosted eval/agent platforms like Braintrust or LangSmith for teams that want a local-first, Git-friendly workflow and don't want their prompts and datasets sitting in someone else's cloud.

Editor's take

Kiln nails an underserved niche: a credible open-source rival to Braintrust and LangSmith that keeps your eval data on your laptop and in Git. The free Python library is the real product; Kiln Pro is the sweetener. For serious agent teams that care about data sovereignty, it's one of the more honest tools in this space.

— The AI Tool Bible editorial team

Pros

✅ MIT-licensed Python library with 4,500+ GitHub stars
✅ Local-first desktop app with Git-versioned datasets
✅ Supports 190+ models across OpenAI, Anthropic, Gemini, Ollama, Bedrock
✅ Covers build, eval, and fine-tune in one workbench
✅ Genuine free tier, not a time-limited trial

Cons

⚠️ Best Pro features (auto-optimization, AI assistant) are rate-limited on free tier
⚠️ Team tier is request-access, not self-serve
⚠️ Desktop-first means it's less collaborative than fully-hosted eval platforms

Use cases

llm-evaluationfine-tuningagent-developmentsynthetic-dataragprompt-optimization

Frequently asked

What is the primary function of Kiln AI?: Kiln AI is a desktop workbench and open-source Python library that bundles RAG, tools, sub-agents, LLM-as-judge evals, synthetic data generation, and fine-tuning into a single local environment.
Which AI models does Kiln AI support?: It supports over 190 models across providers including OpenAI, Anthropic, Gemini, Ollama, Bedrock, and Azure OpenAI, preventing vendor lock-in.
How does Kiln AI handle data storage and collaboration?: The desktop app runs locally on macOS, Windows, and Linux, with datasets versioned in Git. This allows engineers, data scientists, and PMs to collaborate without SaaS lock-in.
What are the pricing options for Kiln AI?: Kiln AI offers a free Individual tier with rate-limited Pro features, a Team tier requiring access requests, and an Enterprise tier with custom pricing, SSO/SAML, and SLAs.
Who should avoid using Kiln AI?: It is not suitable for teams requiring a fully-hosted, browser-based eval platform for non-technical teammates who will not install a desktop application.