CADmium: A local-first CAD program built for the browser

Original Article ↗ Hacker News Discussion ↗

Overall reception

  • Many commenters find the write‑up exceptionally clear, engaging, and motivating.
  • Strong excitement that someone is attempting a modern, open, local‑first parametric CAD, seen as badly needed.
  • Some skepticism that a small team can catch up with decades‑old commercial kernels and tools.

Comparisons to existing CAD tools

  • Onshape is widely praised for UX and performance, but criticized for:
    • SaaS dependency, lack of local‑first capability.
    • Proprietary, high pricing, and prior changes to free tiers.
  • FreeCAD is seen as powerful but:
    • Very inconsistent and confusing in UX.
    • Hampered historically by the “topological naming problem” and OpenCascade fillet/chamfer fragility.
  • SolveSpace is praised as the only truly usable free parametric CAD by some, but lacks key features (e.g., robust fillets).
  • Ondsel is described as a commercial distribution around FreeCAD with UX improvements, new assembly and configuration features, and cloud collaboration.

Technical discussion: kernels, constraints, and performance

  • Truck (the kernel used by CADmium) is seen as promising: a potential open alternative to OpenCascade/Parasolid.
  • Multiple comments emphasize how difficult robust fillets/chamfers and surface offsets are; success there is viewed as a litmus test for kernel maturity.
  • Constraint solving:
    • Debate over 2D vs full 3D constraint solvers; several argue 3D is necessary for assemblies.
    • Claims that large constraint systems are manageable with modern sparse solvers; some think the article overstates performance limits.
    • Existing solvers from SolveSpace and Ondsel are mentioned as usable references.

UX, open source, and learning curve

  • Repeated theme: open‑source tools often have weak, inconsistent UX due to fragmented design and reluctance to enforce a coherent vision.
  • Many recount frustration learning FreeCAD via poor tutorials and fragile workflows; contrast with relatively quick success in Onshape/Fusion.
  • Others note FreeCAD UX and documentation have improved, with better tutorials and active design work.

Architecture & data formats

  • Using the browser is debated:
    • Pro: instant cross‑platform access (desktop, mobile, makerspaces) without installs.
    • Con: some want native binaries; skepticism about matching native performance and integration.
  • Electron is seen as a pragmatic way to get desktop integration given immature Rust GUI stacks.
  • Using JSON for everything gets pushback from people who prefer strongly typed formats like STEP + schemas.

Licensing, openness, and ecosystem

  • Choice of an Elastic‑style license prompts concern; some argue AGPL would be better aligned with “open” while still deterring cloud resellers.
  • Broader worries that any VC‑backed or open‑core product may drift into subscription SaaS and away from truly local‑first use.
  • Desire for:
    • A non‑subscription, reasonably priced or truly free CAD.
    • Preservation of parametric history and constraints in exchange formats (beyond today’s mostly geometric STEP).
  • Some dislike reliance on Discord for project coordination and advocate more open communication platforms.