Kerf vs Pencil

Kerf is a free, open-source CAD workspace that runs on the user's own machine and supports work across 37 engineering domains. Users can describe design changes in plain language or use the Python kerf-sdk and JSON-RPC API. Mechanical design tools include constraint-based sketching, parametric feature history, validated B-rep geometry, drawings, and persistent face references. The workspace also includes FEM analysis, topology optimization, SPICE and RF analysis, CAM toolpaths, and G-code output. Listed outputs include STEP, STL, 3MF, IFC4, Gerber, PDF, DXF, BOM CSV, Touchstone, GDS-II, and firmware binaries. The site describes workflows for mechanical and electronics engineers, BIM architects, jewelry designers, and other engineering users. Kerf runs locally without accounts and keeps Git history for file revisions. Workshop content can be used offline once pinned. Installation options include source or Docker, with release archives listed for macOS arm64, macOS x64, and Linux x64; source installation requires Python 3.11 or later. The chat workflow can use a bring-your-own LLM; no bundled model or paid hosted plan is listed.

Pencil is a browser-based AI design and commerce platform for jewelry, connecting product design, manufacturing files, and online shopping experiences. Design tools include editable templates, stone settings, custom 2D and 3D uploads, AI-generated 3D elements, and advanced parameters. Designs can be downloaded as production-ready 3D STL files. The Professional plan includes an e-commerce and product photo generator, and the Design page says users can create studio-quality product photos. Pencil Shop adds ring and pendant website builders, lead capture, quoting, live pricing, and add-to-cart tools; configurators can be deployed on platforms such as Shopify and Wix through an app integration. Enterprise includes headless API access for making existing products configurable, along with custom tools, parametric templates, wholesale markup tools, and a custom-trained AI design agent. The free plan has 0 AI credits and a three-design limit. Professional costs $39 a month, Pencil Shop costs $199 a month, and Pencil Shop Pro costs $499 a month. Enterprise pricing is custom.