Comparison / Onshape alternative
Private documents by default. Native AI agents. $29/mo, not $1,500/yr.
Onshape proved browser CAD could be real. solidSF takes the next step: a custom Rust kernel, native AI agents that drive the feature tree directly, and privacy that does not require a $1,500/yr Professional seat. If you are searching for a private Onshape alternative or a browser CAD like Onshape but private, this page is the long answer.
Onshape's free tier requires that every document you create be public. Onshape's own public documentation policy spells this out: free accounts publish their work to a public document repository where any other Onshape user can open, fork, and study it. For a hobbyist sharing a parametric vise that is fine. For a startup designing a product, a freelancer working under NDA, a contractor doing defense subcontract work, or a student protecting a thesis project, it is not.
The honest workaround in the Onshape world is to pay $1,500 per user per year for Onshape Standard, or $2,500 per user per year for Onshape Professional. Both keep documents private. Neither is a low bar for an individual engineer or a small team that just wants to draw a bracket in a tab without publishing it to the world.
solidSF inverts the default. Every solidSF document on every paid plan is private by default. New users can evaluate the full product for 48 hours, and saving starts when the account subscribes or receives BETA/invite access. There is no "free but public" trap. The same engineering surface — feature tree, sketches, constraints, drawings, CAM — is available at $29/mo with privacy already on.
This single shift changes who can use the product. Students working on competition vehicles can keep their part files private without paying a Professional license. Two-person hardware startups can iterate on a prototype enclosure without exposing the geometry to a competitor's search. Consultancies can hold client work behind a normal NDA without architecting a separate paid account per client. The economics flip from "pay $1,500/yr to keep your work confidential" to "your work is confidential by default, and pricing is decoupled from privacy."
Onshape has shipped an AI advisor and continues to extend it. It is useful for asking questions about the product. It is not, as of writing, a system that drives Onshape's feature tree end-to-end from a natural language prompt.
solidSF ships native AI agents as a first-class surface. The agent has 55 registered CAD and drawing tools — sketch operations, constraints, extrudes, revolves, sweeps, lofts, fillets, chamfers, patterns, hole wizard, sheet metal, drawings, CAM setup, import, export, validation. The agent operates the real kernel. You can ask in natural language for a bracket with specific bolt patterns, or a drawing view with hole callouts, and watch the feature tree assemble in the workspace.
The training data comes from real solidSF sessions. Every interaction generates new trajectories that feed the next training run. Competitors with chat overlays bolted onto a different vendor's kernel cannot easily close that gap, because their agent does not own the geometry operations end-to-end.
If your team's day-to-day starts to involve agentic CAD — generating parts from specs, regenerating drawings after a change, batch-fixing a thousand fasteners across an assembly — the difference between "advisor that suggests next steps" and "agent that performs the next steps" compounds fast.
| Capability | solidSF | Onshape |
|---|---|---|
| Browser-native | Yes | Yes |
| Install required | No | No |
| Trial save policy | Saving disabled until subscribed | Public documents required on free tier |
| Pro entry price | $29/mo ($348/yr) | $1,500/yr Standard, $2,500/yr Pro |
| Native AI agents | 55 registered CAD tools | AI advisor |
| CAM included | Yes (contour, pocket, drilling, adaptive) | Manufacture add-on tier |
| Drawings included | Yes (GD&T, hole callouts, BOM) | Yes |
| PDM/Vault | Built in (revisions, locks, where-used) | Versioning + branching native |
| Mobile browser | Yes (read + edit) | Yes (read + light edit) |
| iPad | Browser-native | Native app |
| Custom kernel | Rust B-rep, in-house | Parasolid (licensed) |
| Open-source posture | Kernel components on public roadmap | Closed |
Most teams moving off Onshape do not need a perfect history transfer. They need geometry, drawings, and a clear path to keep building. Onshape can export to STEP AP203 or AP214, Parasolid x_t/x_b, STL, and a handful of other neutral formats. solidSF reads all of the geometry formats and rebuilds a workable parametric history on import.
Onshape is an excellent product and there are situations where it is the right pick over solidSF today. If your team has deeply standardized on Onshape branching and merging for hundreds of engineers, if you have purchased and customized Onshape's enterprise features around release management and global supply chain integration, if you have direct PLM bridges to Siemens Teamcenter or Dassault Enovia plumbed against Onshape's APIs, or if your design partners and contractors all already operate inside Onshape with locked-down enterprise permissions — the migration cost may exceed the price-and-privacy gain in the short term. solidSF is for teams that want to switch on the engineering side as well, not just on the seat-license side. The honest read: Onshape Enterprise with deep PLM integration and a 200-engineer footprint is a real piece of infrastructure, and ripping it out for any browser CAD requires a transition plan, not just a price comparison.
The fastest way to decide is to draw something. Sign in, import a STEP file from Onshape, and try a single feature edit and a single drawing view.