OpenCAE

OpenCAE is an engineering-preview, local-first browser CAD/CAE workspace for structural and thermal simulation. Import CAD or create an analytic STEP part, define a study, mesh and solve it in the browser with OpenCAE Core, inspect the results, and export a self-contained project or report.

The workspace supports linear static stress, transient structural dynamics, modal analysis, and steady-state thermal conduction. Built-in samples, local .opencae.json project files, STEP/STP/STL/OBJ uploads, browser-local solves, selected-state CSV/VTU export, and HTML/PDF reports work without a production API or cloud solver.

Privacy: projects, geometry, meshes, and results never leave the browser. The only optional server flow is the consent-gated, client-side-encrypted 30-day recovery backup (the server stores ciphertext it cannot read). The deployed app also sends anonymous usage analytics (page views and outbound-link clicks) to Plausible; no project or simulation data is tracked, and you can turn it off anytime from the Storage card in the toolbar.

Local Development

Install dependencies and start the API and web app from the repo root:

pnpm install --frozen-lockfile
pnpm dev

OpenCAE Core packages live in this monorepo under packages/*; no sibling checkout or pin bootstrap is required.

pnpm dev starts:

• API: http://localhost:4317
• Web: http://localhost:5173

The API creates and seeds the local SQLite database if needed. The web app can create a blank project, open a local .opencae.json project file, load bracket/beam/cantilever samples, or upload STEP, STP, STL, and OBJ models for the local viewer.

The web app does not call the API. Since the July 2026 local-first move (docs/cloud-retirement.md), the workspace creates projects, meshes, solves, and writes reports entirely in the browser; it makes no request to /api. apps/opencae-api and the services/* implementations behind it are a separate, independently runnable reference backend over the same schema — useful for inspecting the data model or driving the flow over HTTP, but not part of the production path. pnpm dev starts both so the reference backend stays exercised; running only pnpm --filter @opencae/web dev gives you the full product.

Security note: the reference API has no authentication or tenant isolation by design. It binds 127.0.0.1 by default and must stay loopback-only; never expose it as a shared or network-reachable service. The server logs a warning if started on a non-loopback host.

Current Workflow

OpenCAE guides a study through Model, Material, Supports, Loads, Mesh, Run, Results, and Report steps:

• Choose a static stress, dynamic structural, modal, or steady-state thermal study.
• Start from a blank project, an analytic parametric STEP part, or a bracket, beam, or cantilever sample.
• Upload STEP, STP, STL, or OBJ geometry; inspect selectable faces; show dimensions; and adjust model orientation.
• Assign starter materials, including additive-manufacturing print settings that affect effective material properties.
• Add structural supports, temperature boundaries, loads, and multi-body connections as the study requires.
• Generate coarse, medium, fine, or ultra volume meshes for local analysis.
• Run local simulations with progress events, logs, cancellation, result artifacts, HTML reports, and PDF reports.
• Inspect stress, displacement, safety factor, velocity, acceleration, natural frequencies, mode shapes, temperature, and heat flux where available.
• Play dynamic result frames with cached playback preparation for smoother browser rendering.
• Save a self-contained local project file with embedded uploaded model data and completed results.

Useful Commands

pnpm db:migrate
pnpm db:seed
pnpm reset:local
pnpm build
pnpm typecheck
pnpm test
pnpm verify:perf
node scripts/check-production-health.mjs

Cloudflare Worker Deploy

The production Cloudflare target for cae.esau.app serves the Vite web app from Workers Static Assets. Simulations run entirely in the browser with OpenCAE Core — the Worker hosts no solver. If browser autosave overflows, the app can ask for explicit permission to upload a client-encrypted 30-day recovery snapshot; the Worker never receives its decryption key. (The former OpenCAE Core Cloud container/R2 solve path was retired in July 2026; see docs/cloud-retirement.md.)

pnpm install --frozen-lockfile
pnpm deploy:cloudflare

Build and deploy environments use pnpm build:core to build the in-repo OpenCAE Core packages before the web bundle. Production deploys require only this repository plus the checked-in lockfile; there is no runtime or build-time fetch of a second repo.

Production deploys use the default wrangler.jsonc (static assets, security headers, and the encrypted recovery-backup binding; no solver bindings).

For a separate non-production static Worker deploy, use:

pnpm deploy:cloudflare:static:dry-run
pnpm deploy:cloudflare:static

That static path uses wrangler.static.jsonc, which targets opencae-static and intentionally omits the production custom domain routes.

For Cloudflare Builds, use:

Build command: pnpm run build
Deploy command: npx wrangler deploy

pnpm deploy:cloudflare is also valid as a deploy command. Do not use npx wrangler versions upload for the production Worker: version uploads cannot apply the retired container Durable Object cleanup path and can leave Cloudflare rejecting stale OpenCaeCoreCloudContainer state. Do not use the static deploy command for the production Worker.

If Cloudflare rejects a deploy with code 10064 for OpenCaeCoreCloudContainer, run the one-off cleanup deploy from an authenticated Wrangler session:

pnpm deploy:cloudflare:retired-do-cleanup

That records the retired Durable Object delete-class migration server-side. After it succeeds, return to the normal npx wrangler deploy / pnpm deploy:cloudflare path.

Production Uptime

The live app runs at https://cae.esau.app. Uptime monitors should check the Worker health endpoint:

curl -fsS https://cae.esau.app/health

The scheduled Production Health workflow checks this contract every 30 minutes and powers the badge at the top of this README. It requires HTTP 200 plus the expected Worker, service, and solverRuntime: "browser-opencae-core" fields, so a generic success page cannot produce a false green result.

This endpoint proves that the production Worker is reachable and serving the expected local-first release contract. It is not a separate solver-readiness probe: the solver ships inside the app bundle and runs in the browser. Retired cloud solve routes return HTTP 410.

Workspace Layout

• apps/opencae-web - React/Vite CAD workspace for static and dynamic structural workflows.
• apps/opencae-api - Fastify reference API for projects, uploads, studies, jobs, artifacts, reports, and service orchestration. Not on the production path; the web app does not call it.
• packages/* - OpenCAE Core model, examples, CPU solver, WebGPU solver, and viewer packages. (The never-implemented solver-wasm placeholder was removed in July 2026; browser WebAssembly is Gmsh meshing in libs/opencae-mesh-intake.)
• libs/* - Shared schema, units, materials, storage, jobs, validation (study-core), database, mesh intake, solve pipeline, and core-adapter packages.
• services/* - CAD, mesh, solver, and post-processing reference implementations behind the reference API, plus a legacy CalculiX container note. (The opencae-core-cloud runner mirror was removed in the July 2026 cloud retirement.)
• runners/opencae-runner-local - Local runner package for job execution flows.
• examples/* - Sample project documentation and fixtures.
• docs/* - Architecture, local development, file format, validation, and user guide notes.
• infra/local/* - Local SQLite, storage, and jobs setup notes.
• data/* - Local runtime data directories for the reference API: artifacts (including each project's uploads), logs, reports, and sqlite state.

Simulation Flow

OpenCAE treats CAD entities as the source of truth. Meshes are generated artifacts, while results and reports are immutable study-run artifacts. Loads, supports, contacts, and named selections bind to CAD topology references so the data model can survive backend changes without rewriting the user workflow.

The built-in bracket, beam, and cantilever demos ship with Aluminum 6061 and 3D-printing material presets, supports, payload/force loads, generated mesh summaries, and local report artifacts.

Solver Attribution

Production solving runs in the browser with OpenCAE Core and is labeled as local computed FEA. Results must carry opencae_core_fea, computed result provenance, and actual_volume_mesh or structured_block_core mesh provenance; preview estimates must never be displayed as production FEA. Results solved on the retired OpenCAE Core Cloud (before July 2026) keep their historical cloud provenance labels — old data stays truthfully attributed.

Documentation

• Architecture
• Local development
• User guide
• File format
• Validation
• Cloud retirement (2026-07)

License

OpenCAE source code is licensed under the Apache License 2.0.

OpenCAE may invoke or distribute separately licensed third-party tools and libraries, including OCCT/occt-import-js components. Those components are not relicensed under Apache-2.0. See NOTICE and THIRD_PARTY_NOTICES.md for details.

Copyright 2026 Esau Engineering. The OpenCAE name and logo are trademarks of Esau Engineering.

Scope

OpenCAE is still an engineering preview. OpenCAE Core results are development-oriented analysis outputs and should not be treated as certified analysis. Native CAD, meshing, and post-processing support continue to evolve behind the existing service boundaries.