Open your subnet layout JSON in the Visual Subnet Calculator inside Simple Browser — next to your code, with a short shareable ?c=v1… link (same format as Copy Link on the web app).
Quick start
- Open a workspace that contains a v0-subnets JSON export (optional).
- Command Palette → Subnet: Preview JSON (
Cmd+Shift+P/Ctrl+Shift+P). - Simple Browser opens
https://v0-subnets.vercel.app/?c=v1…with your layout loaded.
Tip: bind a shortcut to network.subnetPreview.open.
What it does
- Opens the calculator in Simple Browser (no external browser required).
- Uses the focused
.jsonwhen it is a valid v0-subnets export; otherwise finds configs by glob. - Builds a compressed preview URL in-process (
deflate-raw→?c=v1…). - Falls back to an empty calculator when no config is present (configurable).
- No telemetry from the extension. Reads workspace JSON locally only.
Which file is opened?
| Situation | Result |
|---|---|
| Focused editor has valid v0-subnets JSON | That file |
| No valid JSON focused | Latest match of network.subnetPreview.configGlob (default docs/subnet-config-*.json) |
| Primary glob finds nothing | network.subnetPreview.configFallbackGlobs (default **/*subnet-config*.json) |
| Multiple matches | Latest path (sorted); set promptWhenMultiple to pick |
| No config in workspace | Empty calculator if openEmptyWhenMissing is on |
Re-run the command after you save JSON changes — an already-open Simple Browser tab does not auto-refresh.
Example JSON
Compatible with exports from v0-subnets.vercel.app:
{
"networkAddress": "10.0.0.0",
"maskBits": "16",
"subnets": [
{
"networkAddress": "10.0.0.0",
"maskBits": 24,
"prefix": "app-uat",
"color": "blue"
}
]
}
Minimum shape: networkAddress + subnets[] (each subnet needs networkAddress).
Settings
| Setting | Default | Description |
|---|---|---|
network.subnetPreview.configGlob |
docs/subnet-config-*.json |
Primary workspace glob |
network.subnetPreview.configFallbackGlobs |
["**/*subnet-config*.json"] |
Extra globs if primary finds nothing |
network.subnetPreview.promptWhenMultiple |
false |
Show a picker when multiple configs match |
network.subnetPreview.openEmptyWhenMissing |
true |
Open empty calculator when nothing matches |
Privacy & security
| Topic | Behavior |
|---|---|
| Telemetry | None from this extension |
| Workspace files | Read locally via the VS Code API only |
| Preview host | Fixed to https://v0-subnets.vercel.app/ |
| URL contents | Layout data (CIDRs, names/notes, colors) is sent in the query string to load the page — avoid secrets or personal data in notes |
| Path safety | Config must stay inside the workspace; JSON validated and capped at 1 MiB |
| Errors | Generic toasts (no filesystem paths) |
Requirements
- VS Code 1.80+ or Cursor with Simple Browser
- A workspace folder open (not a single loose file)
Links
- Calculator: v0-subnets.vercel.app
- Marketplace: newbmiao.subnets-preview
License
MIT