Windows Disk Analyzer
Interactive sunburst and treemap charts powered by D3. A native HDD scanner that eliminates per-file syscalls. Live scan progress. Open source, free forever.
Features
Two interactive D3-powered views. Click any segment to drill into a directory, press Esc to navigate back up. Every file and folder visualized in proportion to its size.
Files and sizes accumulate in real time as the scanner works. A progress overlay keeps you informed — no waiting blindly for a result to appear.
Auto-detects drive type via WMI. On HDDs, a native C++ addon uses FindFirstFileExW to read file sizes from directory entries directly — eliminating all per-file stat() syscalls.
Performance
Inspired by the XN-Graph SIGIR '25 paper on disk-based nearest-neighbor search, the scanner applies an In-Memory First (IMF) strategy: instead of waiting on each I/O batch, it keeps 64 requests in flight simultaneously, eliminating the idle gap between completions.
On HDDs, a native C++ N-API addon (FindFirstFileExW) fetches file sizes
directly from directory entries — no additional stat() per file.
On SSDs, the IMF scanner runs with unlimited parallelism.
| Workload | Before | After | Gain |
|---|---|---|---|
| 3M files (large tree) | 81.1s | 68.8s | 1.18× |
| Smaller directories | baseline | — | 1.92× |
| Heap allocation | ~100% | ~27% | −73% |
Technology