What is Kiln?
Kiln is an AI workbench for teams building AI systems. It combines a free desktop app for macOS, Windows and Linux with an MIT-licensed Python library. The app lets you build tasks with structured output, RAG over your documents, reusable skills, tools and MCP, and sub-agents, then measure quality with evals, golden datasets, human ratings and LLM-as-judge scoring.
In practice you can compare models and prompts against your own evals, auto-tune prompts to those evals, generate and label synthetic data, and distill results into smaller models through fine-tuning. Datasets are stored locally and can be versioned through a git repo you control, and the same tasks can be deployed in production with the Python library. A paid Kiln Pro tier adds an AI Assistant, auto-generated evals and the Kiln Optimizer, running on Kiln's servers.
Key features
- Evals with LLM-as-judge, golden datasets and human ratings
- Automatic prompt optimization against evals
- Fine-tuning and synthetic data generation
- RAG over documents with chunking and retrieval
- Skills, tools, MCP and sub-agents
- Git sync of datasets and open-source Python library
Who is it for
- AI engineers
- Data scientists
- Product managers and QA teams
- Enterprise teams needing SSO and contracts
Pros and cons
- Free desktop app and MIT-licensed Python library
- Datasets stay local and sync through a git repo you control
- Kiln Pro features run on Kiln's servers and are rate limited on the free tier
- Advanced features such as Kiln Optimizer are reserved for Team and Enterprise plans
Kiln pricing
| Plan | Price | Includes |
|---|---|---|
| Individual | 0 USD | Standard models and rate-limited AI Assistant, standard auto-generated evals, community support |
Prices copied from the vendor website, checked October 12, 2026. Currency as shown by the vendor; taxes may apply.
Is Kiln free?
Yes, there is a free plan. Individual: open-source Python library, desktop app (source-available), local datasets with git sync, standard-model Kiln Pro with rate limits, community support.
Kiln alternatives
| Tool | Price from | Free plan | Category |
|---|---|---|---|
 Evaligo | 7 USD/mo | yes | Website & app builders |
 LangChain | 39 USD/mo | yes | Website & app builders |
 Gemini Enterprise Agent Platform | 0,75 USD | ? | Website & app builders |
 GlideOS | 25 USD/mo | yes | Website & app builders |
 Mastra | 250 USD/mo | yes | Website & app builders |
 Pipedream | 99 USD/mo | yes | Website & app builders |
FAQ
What is Kiln used for?
Desktop workbench and open-source Python library for building, evaluating and optimizing AI systems (evals, RAG, agents, fine-tuning) for teams.
Is Kiln free?
Yes, there is a free plan. Individual: open-source Python library, desktop app (source-available), local datasets with git sync, standard-model Kiln Pro with rate limits, community support.
How much does Kiln cost?
The vendor does not publish prices publicly or requires sign-in.
What are the best Kiln alternatives?
Closest alternatives: Evaligo, LangChain, Gemini Enterprise Agent Platform, GlideOS, Mastra.
Data checked October 12, 2026 on the vendor website (getkiln.ai).