Document Persistence | Reference

vcad automatically saves your work to the browser's local storage. Your documents persist across browser sessions and work fully offline.

The .vcad File Format

Documents are saved as .vcad files, which are JSON containing the complete parametric model:

{
  "name": "My Part",
  "parts": [
    {
      "id": "part-1",
      "name": "Main Body",
      "ops": [
        { "type": "box", "width": 100, "height": 50, "depth": 25 },
        { "type": "translate", "ref": 0, "x": 0, "y": 0, "z": 10 }
      ]
    }
  ],
  "instances": [...],
  "joints": [...],
  "materials": {...},
  "sketches": [...]
}

What's Stored

Content	Description
Parametric DAG	Operations reference parent indices, enabling non-destructive editing
Part definitions	Named parts with their operation sequences
Instances	Part placements with transforms for assemblies
Joints	Kinematic relationships between instances
Material assignments	Per-part or per-face materials
Sketches	2D geometry and constraint data

Auto-Save

vcad saves automatically on every change. You never need to manually save.

Action	What Happens
Create new document	Generates name ("Untitled 1", "Untitled 2", etc.), saves immediately
Make any edit	Auto-saves to IndexedDB
Rename document	Updates name in storage
Close browser tab	Your work is already saved

Auto-save is instant. There is no save delay or debounce. Every change is persisted immediately.

Loading Documents

From the Document List

Open the document list to see all your saved documents, sorted by most recently modified. Click a document to open it.

From File Import

To load a .vcad file from your computer:

Use File > Import or drag the file onto the viewport
The file is loaded into a new document
The new document is saved to local storage

Exporting Documents

To share a document or back it up:

Use File > Export or the export button
A .vcad file downloads to your computer
Share this file or import it on another device

Export your important documents periodically. Browser storage can be cleared by the user or browser cleanup tools.

Offline Support

vcad works fully offline after the initial page load. All features remain available:

Create and edit documents
Save and load from local storage
Export files to your computer
Import files from your computer

No network connection is required for any editing operations.

Multi-Tab Behavior

vcad coordinates across browser tabs to prevent conflicts when you have the same document open in multiple tabs.

Scenario	Behavior
Open document in second tab	Second tab shows "locked" warning, opens read-only
Close the editing tab	Lock releases, other tabs can edit
Tab crashes	Lock auto-releases after 30 seconds

Avoid editing the same document in multiple tabs. The lock system prevents data loss but provides a degraded experience.

Storage Management

Documents are stored in the browser's IndexedDB. vcad monitors storage usage and warns you when space is low.

Storage Level	Indicator
Normal	No indicator
80% capacity	Warning message
95% capacity	Blocks new saves until space is freed

Freeing Space

If you run low on storage:

Open the document list
Delete documents you no longer need
Export important documents first as backup

Storage Limits

Browser storage limits vary by browser and device. Typical limits are 50MB-1GB per origin. Large documents (over 10MB) may impact performance.

Edge Cases

Scenario	Handling
Storage full	Warning dialog appears, suggests deleting old documents
IndexedDB unavailable	Falls back to session-only mode with warning (work is lost on tab close)
Corrupted file	Parser validates JSON, shows error on invalid format
Browser data cleared	Local documents are lost; keep exports of important work

Sync Status

The sync indicator shows the current document state:

Status	Meaning
`local`	Saved locally, not synced to cloud
`pending`	Changes waiting for cloud sync
`synced`	Fully synchronized with cloud

Cloud sync is not yet available. All documents are currently local-only. Keep exports of important work.