Lumen
A self-hosted raw photo editor for Mac and iPhone
Privacy Policy
Effective October 2026
In short: there is no Lumen server and no Lumen account. The app only talks to the WebDAV server you configure yourself — never to us. We never receive your photographs, your edits, or any information about you.
Information we collect
None. Lumen has no accounts, sign-in, analytics, advertising or tracking. We don't operate any servers that the app talks to, and we never receive your files, file names, or usage data.
Where your photographs go
- Originals are copied to the WebDAV server you enter in Settings — your own NAS, a Nextcloud or ownCloud instance, a rented box, or your Mac itself in Host mode. That connection is between your device and your server; it never passes through us.
- A local catalog on each device tracks your library, star ratings, flags and collections, and keeps smart previews so you can edit without downloading full-resolution originals every time.
- Every edit is written as a small JSON "sidecar" file next to the photograph on your server — readable, and yours, independent of the app.
Credentials
Your server address and login are stored encrypted in your device's own keychain. We never see them, and they never leave your device except in the connection your device makes directly to your server.
Children
Lumen doesn't collect information from anyone, including children.
Changes to this policy
If this changes, we'll update this page and the date above.
Contact
Questions about privacy? Email [email protected].
Support
Need help? Start here, or email [email protected].
Where things stand
Lumen is in active development. The Mac and iPhone/iPad apps are native Swift — library, Develop, export, the WebDAV host and the preview worker all run without Electron — and currently built from source rather than distributed through the App Store. See the self-hosting guide below for what's involved, or the full overview for what Lumen is and how it compares to Lightroom and Luminar.
Getting started
Prefer a walkthrough? The setup guide covers Tailscale and Lumen together, step by step. The short version:
- Point Lumen at a server. In Settings, enter any WebDAV URL — a NAS, Nextcloud, ownCloud, or a plain WebDAV folder.
- No server yet? On the Mac, turn on Host mode — it becomes the server and preview worker, and your iPhone syncs to it over your local network.
- Import photographs. Raw files, JPEG, PNG, TIFF, WebP and HEIC are all supported; originals upload to your server while a local smart preview keeps editing fast.
- Edit anywhere. Changes sync as small JSON files, typically in a few seconds, so a crop on your phone shows up on your Mac shortly after.
Remote access with Tailscale
Host mode's server speaks plain WebDAV with a password — nothing encrypts that connection on its own, so reach decides who's allowed to even attempt it:
- Tailscale only (the default) — only devices on your own Tailscale network, plus the Mac itself, are let through. Everything else is refused before it can try a password. Tailscale is a free private mesh network: install it on your Mac and your phone, sign into the same account on both, and they get private addresses (100.x.x.x) that only reach each other — no port forwarding, no static IP, nothing exposed publicly.
- Any network — your whole local network can reach the host. Credentials travel unencrypted, so this is meant for a trusted LAN, with a strong password, not for leaving on permanently.
Settings includes a connection check that reports whether Tailscale is installed, your Mac's tailnet address, and which of your other devices are currently online — so a phone that can't reach the library has a concrete answer (install Tailscale, sign in, wake the host Mac) instead of a guess.
Common questions
Can I reach my library away from home?
Yes — that's what Host mode's Tailscale-only reach is for. Install Tailscale on your Mac and your phone, sign into the same account, and your phone can sync from anywhere exactly as it does at home, over an encrypted private connection. See "Remote access with Tailscale" above.
Do I need an account?
No. There's no Lumen account and no Lumen server — only the WebDAV server you point the app at.
What happens if I lose my phone or computer?
Your originals and every edit live on your server, not only on the device. Install Lumen on a new device, point it at the same server, and your library — photographs, edits, ratings and collections — comes back.
Does it work offline?
Yes. Editing works from the local smart preview without a connection; changes sync the next time the app can reach your server.
What raw formats are supported?
19 raw formats via LibRaw — including CR2/CR3, NEF, ARW, DNG and RAF — plus JPEG, PNG, TIFF, WebP and HEIC.
Which devices are supported right now?
Mac (Apple Silicon and Intel, macOS 14+), iPhone, iPad and the iPhone Duo's wide layouts — all native Swift. The apps are in active development and currently run from source rather than through the App Store.
Is my data ever sent to you?
No. Lumen has no servers of its own and no analytics. The only network connection the app makes is directly to the WebDAV server you configure.
Still need help?
Email [email protected] with your device, what you were doing, and what happened.
Documentation
Deeper reference material, for self-hosting or just curiosity.