A free, offline lab sample management tool — one HTML file, no installation, no cloud.
Built for labs that are tired of spreadsheets named
FINAL_v3_USE_THIS_ONE.xlsx.
Locus Arca lets you map your entire freezer infrastructure and track exactly where every sample is stored — down to the individual grid position in a box. It runs as a single HTML file in your browser. No server. No account. No internet connection needed. No admin rights required. All data is saved in a JSON file you control.
- Five-level hierarchy: Freezer unit → Compartment → Rack → Drawer → Box
- Not all levels are required — a box can sit directly inside a unit or compartment
- Location field per freezer unit (room number, building, external storage provider)
- Visual groups for freezer units (e.g. "-20°C devices", "4°C devices") — display only, not part of the sample path
- Three box types: Grid (A1, B2…), Numbered (1, 2, 3…), Freeform (text note)
- Grid boxes: visual position picker, occupied slots marked, no double-booking
- Samples can be stored without a box, or without any storage location at all
- Sidebar shows 📂 Not stored entries automatically when relevant
- Right-click context menu on any tree item: rename, resize, move, delete
- Move an entire rack, drawer, or box — all contents and samples move with it
- Drag & drop reordering within the same level
- Sample ID is optional — the system auto-assigns an internal ID (S-00001, S-00002…) if left blank
- All fields optional: sample type, project, subject ID, collection date, volume, remarks
- Status: Available / Removed / Consumed / Reserved / Disposed
- Multi-position selection in grid boxes (Ctrl+Click) — creates one sample per position with shared metadata
- Autocomplete in all text fields — learns from your own data
- Move samples between locations without re-entering all data
- Full audit log of all create / edit / move / delete / bulk actions
- Checkbox per row — select any number of samples
- Edit selection — update type, status, project or remarks; only checked fields are overwritten
- Move selection — reassign all selected samples to the same new location
- Delete selection — delete all selected samples after confirmation
- Search across all fields simultaneously (ID, system ID, type, project, subject, location, notes)
- Filter by sample type and status
- Sidebar tree acts as an additional location filter — combine all three
- CSV export with selectable columns — 17 fields, choose exactly what you need
- CSV import with template download — missing structure elements (racks, boxes etc.) are created automatically on import; box type auto-detected from position format
- UTF-8 BOM + semicolon separator — opens directly in Excel
- Headers switch with language setting (DE/EN)
- Save directly to file (Chrome/Edge/Opera) or download (Firefox/Safari)
- Backup always opens a Save As dialog
- Confirmation prompt before overwriting an existing file
- Filename shown in title bar
- Dark theme
- German / English language toggle (including CSV headers)
- No admin rights required — runs directly from a local HTML file
- Resizable sidebar
- Download
locus-arca.html - Open it in Chrome or Edge
- Click Demo to explore with example data — or click Lager to set up your own storage structure
- Click + Neue Probe to add your first sample
- Click Speichern to save — choose a location on a shared network drive if multiple people use it
Tip: Drop the HTML file and the JSON database on a shared network drive so the whole team can access it. Only one person should edit at a time — there's no conflict resolution for simultaneous edits.
Everything is stored in a single .json file:
{
"meta": { "appName": "Locus Arca", "sampleCounter": 42 },
"storage": { "freezers": [ ... ], "groups": [ ... ] },
"samples": [ { "_uid": "S-00001", "id": "PR-2026-001", ... } ],
"history": [ ... ]
}Each sample has an internal _uid assigned by the system (never changes) and an optional user-visible id. The file is human-readable plain JSON.
| Browser | Save to file | Notes |
|---|---|---|
| Chrome | ✅ Direct save | Recommended |
| Edge | ✅ Direct save | Recommended |
| Opera | ✅ Direct save | Chromium-based |
| Brave | ✅ Direct save | Chromium-based |
| Vivaldi | ✅ Direct save | Chromium-based |
| Firefox | ⬇️ Download only | Fully functional |
| Safari | ⬇️ Download only | Fully functional |
MIT License — free to use, modify and distribute.
Feedback and issues welcome via GitHub Issues.