Overview

Kerf is a local CAD workspace for people who want to move between engineering design, analysis, and fabrication rather than hand work off between separate tools. Its strongest fit is a technically minded designer comfortable with source-based installation and supplying an LLM for chat; readers seeking a turnkey hosted assistant should look elsewhere.

The workspace spans 37 engineering domains, with workflows for mechanical and electronics engineers, BIM architects, jewelry designers, and others. Users can describe changes in plain language or script the same tool surface through the Python kerf-sdk or JSON-RPC API. Keeping data and Git revision history local is a meaningful advantage for users who want control over files and workflow, though it also puts installation and model choice in their hands.

Key features

Modeling, simulation, and fabrication

Mechanical tools include a constraint-based sketcher, parametric feature history, validated B-rep geometry, drawings, and persistent face references. Jewelry workflows add ring sizing, stone setting, photorealistic rendering, and manufacturing export. That combination makes Kerf unusually broad for a free workspace, but users wanting a narrowly focused design package may have little use for its wider engineering scope.

Kerf also brings FEM analysis, topology optimization, SPICE simulation, RF analysis, CAM toolpaths, and G-code output into the workspace. Export formats include STEP, STL, 3MF, IFC4, Gerber, PDF, DXF, BOM CSV, Touchstone, GDS-II, firmware binaries, and G-code. The range can support work from model creation through production handoff, though it also reflects the demands of a technically diverse toolset.

Code, integrations, and sharing

For repeatable or automated workflows, the Python SDK and JSON-RPC API expose the same tools used through chat. Kerf lists open kernels and tools including JSCAD, OpenCascade, tscircuit, FEniCSx, OpenCAMlib, IfcOpenShell, FreeRouting, and KiCad. Its Workshop uses signed, content-addressed objects over an open protocol; it needs no account or central server, and pinned content can be used offline.

Files and their revision history stay local, and the app runs without accounts. Chat is the main caveat: users bring their own LLM, with no bundled model or paid hosted plan. That suits people who already have a model workflow, but makes Kerf a less direct choice for anyone expecting chat to work out of the box.

Pricing

Kerf is free: its Free plan is free, is MIT licensed, runs locally, and requires no account or billing. There is no paid tier described; the chat workflow still requires users to provide their own LLM. For a free tool with parametric modeling, jewelry tools, rendering, and manufacturing export, the plan is generous, but it does not remove the setup and model-sourcing responsibilities.

Platforms

Kerf is available for Linux and macOS, with API, web, and self-hosted platforms also listed. Installation is supported from source or Docker; release archives are listed for macOS arm64, macOS x64, and Linux x64. Source installation requires Python 3.11 or later, while the embedded SQLite setup needs no database server. This suits users comfortable managing a local development-style installation better than those looking for a conventional one-click hosted service.

Who it's for

Kerf is a strong candidate for engineers and designers who want local control, scripting access, and one workspace spanning CAD, simulation, and manufacturing. Its listed jewelry features make it relevant to jewelry designers as well. It is a poor fit for people who need a bundled conversational model or prefer a hosted, account-based workflow.

Pros and cons

Pro: Free, MIT-licensed access to parametric CAD, jewelry tools, simulation, and manufacturing output makes the scope unusually broad without a subscription.
Pro: Local files and Git history, plus account-free Workshop sharing, keep data and revisions under the user's control.
Pro: Python and JSON-RPC access provide a route to automate the same tools available through chat.
Con: Chat requires a user-supplied LLM, so conversational design is not ready to use by itself.
Con: Source installation requires Python 3.11 or later; that is a real setup hurdle for users who want a conventional desktop installer.

Alternatives

For jewelry-focused options, browse Jewelry Design Software. Rhino 3D is worth considering if you prefer paid software with a permanent-license option and a free plan and trial. Diatech Studio may suit a mobile-first user: it lists Android and iOS alongside web and self-hosted access, with a free plan that includes AI features and 25 images.

3Design CAD is another paid, jewelry-oriented option for users who want a product with a free trial. Pencil may be a better fit for web-based jewelry design, but its free plan limits users to three designs and provides no AI credits. ZBrush is an alternative for users interested in sculpting, with a free iPad plan that includes 28 brushes.

CounterSketch is a paid option with a free trial for users who value tech support, an online academy, and library updates. Drakon may suit Windows or web users who prefer buying Copilot credits, with listed one-time options of 20.00 EUR for 5,000 credits and 50.00 EUR for 12,500. Carveco is a Windows-only paid alternative with a 30-day free trial for new customers.

Verdict

Choose Kerf if you want a free, local engineering workspace that connects parametric design, analysis, scripting, and manufacturing output. Its breadth and local history are compelling for users comfortable installing it and bringing their own LLM. If you need ready-to-use chat or a conventional hosted workflow, choose another tool.

	Kerf	Pencil
Free plan	Yes	Yes
Paid from	Free	$39/mo
Platforms	api, Linux, macOS, self-hosted, Web	api, Web
Free plan	Yes	Yes
Parametric modeling	Yes	Yes
Ring sizing tools	Yes
Stone setting tools	Yes	Yes
Photorealistic rendering	Yes	Yes
Manufacturing export	Yes	Yes
Supported platforms	hybrid	browser
File export formats	STEP, STL, 3MF, DXF, G-code	STL
Paid from		39 /mo

Kerf vs Pencil

Kerf

Pencil