Open Lumen in a browser

You're seeing a preview, not the app. Previews can't run code, so nothing here will respond to taps.

Try this first

  1. Tap Share ⬆︎ at the bottom of this preview.
  2. Look for Open in Safari, or Copy to Chrome / Firefox / Edge. Scroll the row of apps — it's often hidden off to the right.

No browser in that list?

Apple doesn't let this preview hand a local file to Safari. Any one of these works instead:

  1. Ask for a link. Whoever sent this can host the same file anywhere — then you just tap the link. This is the easiest fix by far.
  2. Same Wi-Fi? Ask them to open Lumen on their computer, go to Share this app, and read out the address shown there.
  3. Install any other browser free from the App Store — Chrome, Firefox and Edge all add a “Copy to…” option to that Share menu.
  4. Downloaded this in Safari? Open Safari, tap the Downloads arrow, and tap the file there. Safari runs it properly from its own downloads.

Then do this once

With Lumen open in Safari, tap Share ⬆︎ then Add to Home Screen. It becomes a normal app icon, opens instantly, and never needs the internet again.

Android, Windows or Mac

  1. Right-click or long-press the file.
  2. Choose Open with, then any browser.

Nothing is wrong with the file. It just needs a real browser.

Lumen

Move a file between two devices on light alone. No network, no cable, no account.

This whole app is one HTML file. Send it to anyone — AirDrop, Quick Share, WhatsApp, email, USB. No install, no archive to extract, no server, no account, and no shared network.

They can pass it on to someone else too. Lumen copies itself.

Checks the camera, decoder and screen settings so there are no surprises later.

1. Open this file on both devices.

2. On the device holding the file, tap Send a file and pick it. Turn the brightness up.

3. On the other device, tap Receive a file and point its camera at the first screen.

4. Hold steady. When it says complete, tap Save, then Stop on the sender.

The transfer is pure light — nothing crosses a network, so both devices can be in airplane mode. Dropped frames repair themselves, so a wobble costs a moment, not the transfer.

Send
Choose a file
or drag one here
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Starting camera…

Transfer complete

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