H5 Viewer
Visualize HDF5 files directly in VS Code — optimized for Remote SSH with on-demand data loading.
Chinese / 中文文档
Key Features
- Line plots — 1D datasets with error bars, auxiliary signals, and CSV export
- Heatmaps — 2D datasets with multiple colormaps, complex number support, and axis controls
- Tables — Matrix view for numerical and compound datasets
- RGB images — Direct visualization of RGB datasets
- 3D slicing — Navigate slices of 3D+ datasets interactively
- NeXus support — Automatic interpretation of NXdata groups and axes
- Metadata inspector — Attributes, chunk layout, compression filters, and data types
- Search — Find entities across the entire file tree
Remote Optimization
This is a fork of vscode-h5web with a redesigned architecture for remote development.
The Problem
The original extension transfers the entire HDF5 file from the remote server to the local browser for parsing. A 500 MB file means 500 MB of network transfer before anything renders. Files over 2 GB cannot be opened at all.
The Solution
H5 Viewer runs the HDF5 parser (h5wasm) on the remote server (Extension Host) and sends only the requested data slices to the local webview via VS Code's message passing. The file never leaves the server.
|
Original |
H5 Viewer |
| Open a 500 MB file |
Transfer 500 MB, then parse |
Parse on server, transfer ~10 KB metadata |
| Switch dataset |
Instant (in memory) |
RPC request (~ms latency) |
| File size limit |
2 GB |
None |
| Remote experience |
Slow |
Fast |
Supported File Extensions
The viewer opens automatically for: .h5, .hdf, .hdf5, .hf5, .nx, .nxs, .nx5, .nexus, .cxi, .nc, .nc4, .loom, .jld2, .h5ebsd, .edaxh5, .oh5, .dream3d, .geoh5, .h5oina, .h5ad.
For other extensions, right-click the file and select Open With... > H5 Viewer (any extension).
To set H5 Viewer as default for additional extensions:
"workbench.editorAssociations": {
"*.foo": "h5viewer.viewer"
}
Compression Plugins
Supported HDF5 compression filters: Blosc, Blosc2, Bitshuffle, BZIP2, JPEG, LZ4, LZF, ZFP, Zstandard.
Plugins are loaded automatically on the server side — no configuration needed.
The extension is fully cross-platform. Both the HDF5 parser and compression plugins are compiled to WebAssembly, so a single package works on x86_64 and ARM64 (Linux, macOS, Windows).
Architecture
Remote Server Local Machine
┌──────────────────────┐ ┌──────────────────────┐
│ Extension Host │ │ Webview (Browser) │
│ (Node.js) │ │ │
│ │ postMessage │ │
│ h5wasm ──> HDF5 │ <── request │ DataProvider │
│ (reads disk │ ──> response │ getEntity() │
│ directly) │ (data slice)│ getValue() │
│ │ │ │
│ Compression plugins │ │ @h5web/app renders │
│ loaded locally │ │ visualizations │
└──────────────────────┘ └──────────────────────┘
Installation
From GitHub Release:
- Go to Releases
- Download the
.vsix file
- In VS Code:
Ctrl+Shift+P → Extensions: Install from VSIX...
From source:
git clone https://github.com/NieeiM/H5-Viewer.git
cd H5-Viewer
pnpm install
pnpm build
pnpm dlx @vscode/vsce package --no-dependencies --allow-missing-repository
Credits
Built on top of H5Web and h5wasm by ESRF (European Synchrotron Radiation Facility).
License
MIT
