Lite (free): open big JSON files in a fast, read-only, lazy-loading tree. Expand nodes, see key/type/preview, copy JSONPath. Scanning runs in a worker thread. 100% offline: pure JS, no telemetry.
Installation
Launch VS Code Quick Open (Ctrl+P), paste the following command, and press enter.
Open big JSON files (tens to ~100 MB) in a fast, read-only tree. Expand and collapse nodes, see each key, its type and a short value preview, and copy the JSONPath of any node. Large JSON Desk Lite is free, including Copy JSONPath.
100% offline. Pure JavaScript, no telemetry, and no network requests. The webview's Content Security Policy allows only the extension's own local script and stylesheet.
How it works
The file is scanned in a worker thread, so the editor stays responsive. No full syntax tree is built. Only the direct children of a node are listed when you expand it, 500 at a time, with a "Load next 500" link.
The viewer is read-only: it never edits or saves your file, and values are shown exactly as written.
The status bar shows the file size and the scan time.
Use
Right-click a .json / .geojson / .har file → Open Large JSON Tree, or run Large JSON Desk: Open Large JSON Tree, or use Reopen Editor With… → Large JSON Tree.
Click a node, then Copy JSONPath (toolbar button, command, or Ctrl+Shift+Alt+J / Cmd+Shift+Alt+J). Example: $.items[42].tags[1], $['my key'].
Lite vs Pro
Feature
Lite (free, this extension)
Pro (add-on, $12 one-time)
Read-only lazy tree for large JSON, scanned in a worker thread
✓
✓
Key / type / value preview, expand & collapse, paged children
Tested with synthetic files up to 100 MB (first 500 children in about 0.25 s on a dev machine). The whole file is read into memory in a worker (about 2× file size), so very large files (roughly 500 MB+) are not supported yet.
Rows stay in the view as you expand more nodes (no windowed virtualization yet). Collapse big branches you are done with.
Expanding a node rescans that node's span. Very wide arrays (1M+ items) open the first page more slowly.
Copy JSONPath works on the node selected in the tree, not from the cursor in the normal text editor.
Read-only by design: edit the file in the normal text editor.
Opens as an option: your default JSON editor does not change.
Privacy
No data leaves your computer. No telemetry, no network requests, no accounts.
