Tens of thousands
of photos. One fast app.
Local · NAS · Apple Photos in one fast, native app.
Proven daily on a 67,000-photo library.
Apple Silicon · Intel · Open Source (MIT)
Local · NAS · Apple Photos in one fast, native app.
Proven daily on a 67,000-photo library.
Apple Silicon · Intel · Open Source (MIT)
Why Lumen
Tested daily against a 67,000-photo NAS library. Folders open in 1 ms on average, and launch shows your photos immediately — no loading screen.
Local folders, NAS, and Apple Photos (iCloud) side-by-side in a single window. The gap Photos.app and generic viewers leave — filled.
Crop · resize · rotate · merge · watermark — all saved as new files, originals untouched (overwrite is opt-in). Favorites, tags, and ratings are stored separately from the source files.
Features
All your scattered photos in one place. iCloud-only photos download on demand; GPS photos cluster on a map by zoom level.
Go full-screen and stay there. The fastest culling flow for photographers:
Crop (free or locked ratio) · rotate / flip · straighten · resize / square canvas (letterbox fill). Large edit canvas with zoom and precision crop, output-size preview. Always a new file.
Combine multiple photos horizontally, vertically, or in a grid (drag to reorder, set rows). Text or logo watermarks (position · color · opacity) — in the editor, merge tool, and batch export.
Resize, apply canvas rules, and stamp watermarks across many photos at once and export to a folder. Originals stay untouched.
Albums · tags · star ratings · color labels · reject flag · smart collections (favorites, recent, today, duplicates). Originals never modified.
Even on a NAS volume with no Trash, deletes move to a hidden .LumenTrash kept for 30 days instead of vanishing. Every delete gets a 10-second Undo that restores the files, ratings, and album memberships.
Search by filename, tag, or camera model. Filter by star rating, label, location, camera (e.g. SONY), and hide-rejected toggle.
System share sheet, export original / resized / zip, bulk rename, set as desktop wallpaper.
Performance
Every folder opens instantly, and your photos are on screen the moment the app is. The table below is all measured, not promised.
Measured on a real library — 67,676 photos · 638 folders · Synology NAS (SMB) · Apple Silicon. These are not synthetic benchmarks: every number comes from automated runs against this library.
| Test | Result |
|---|---|
| Launch → grid fully populated with thumbnails | 1–2 frames after the window appears (no loading screen) |
| Library cache decode (67,676 photos) | ~100 ms |
| Opening folders — all 644 folders & albums in sequence | mean 1 ms · p95 3 ms · max 9 ms |
| First folder click right after launch | ~4 ms |
| Click a photo → info panel update | ~3 ms |
| Select All (⌘A, 67,676 photos) | ~0.2 s |
| Search — filter + sort across 67k | 0 main-thread blocking (runs in background) |
| Bulk add to album (10k into a 20k album) | ~0.2 s |
| Bulk remove from album (10k of 20k) | 17 ms |
| Bulk favorite/rate (20k photos) | ~0.4 s (single transaction) |
| Thumbnail-size slider · window resize | no stalls (GPU-scaled) |
| App size | 10 MB installed · 3.5 MB download |
| Memory (browsing the 67k library) | ~240 MB · ~380 MB after full-size viewing (bounded by cache limits) |
| CPU | 0.0% idle · 16–27% while continuously scrolling a 58k folder |
| Heap analysis (leaks/heap) | 0 memory leaks in app code |
Method: 120 Hz main-thread hitch monitor + frame-by-frame screen capture + profiler sampling, as of v0.4.0. The whole process is documented in the release notes.
Memoized lists · folder index · debounced navigation · background thumbnail warming · lazy EXIF indexing · progressive image loading
Reliability
A tool you run on a huge library every day owes you one promise first: your photos and your organizing work are safe.
Every delete gets a 10-second Undo. On a NAS or any volume with no Trash, files move to .LumenTrash for 30 days instead of vanishing. No feature ever modifies your original files.
Zero memory leaks · cache limits prevent OOM. Zero-byte and corrupt files, symlink loops, unicode and very long filenames are all handled safely.
111 automated tests gate every change, and it runs daily on a real 67k-photo NAS library. If a metadata write fails, it tells you instead of silently dropping it.
Privacy
Lumen makes exactly two kinds of network connections — a once-a-day update check against GitHub, and the NAS/iCloud content you open yourself. That's it.
Zero analytics, telemetry, accounts, or ads. Zero photos uploaded. There is no server.
Ratings, tags, and albums live in a single local SQLite file. Your original photo files are never modified.
If it ever crashes, only the version and stack trace are saved to your Mac; whether to send it as a GitHub issue is your choice on the next launch. Nothing is sent automatically — no file paths or photo data are included.
Download
Install via Homebrew · macOS 14 (Sonoma) or later · Free
brew tap rescenedev/tap
brew trust --cask rescenedev/tap/lumen-photos
brew install --cask lumen-photos
xattr -dr com.apple.quarantine "/Applications/Lumen.app"
git clone the repo, then run ./Scripts/make_app.sh — no Xcode needed, just Command Line Tools.
Sponsor
Lumen is free and open source, and will stay that way.
A small sponsorship goes a long way toward the next update.