Your clipboard on every device

With clipboard sync on, what you copy on one Mac is ready to paste on your other Macs and shows in your Library on the web, so you can copy a PDF at home and paste it at work, or copy something on your phone and paste it on your Mac a moment later. Everything is encrypted end to end: only your devices hold the key, catu never does.

Clipboard sync is part of the Web app plan.

Turn it on#

1. Click the catu icon in the menu bar, then click “Settings…”.
2. Open Privacy.
3. Turn on “Sync clipboard to catu.app” and confirm with “Sync Clipboard”.

If you are not signed in yet, catu asks you to sign in with Apple first. Sharing and sync use the same account.

From now on, your last 50 copies go to catu.app a moment after you copy them. Pinned items stay beyond the 50.

What is synced, and what is not#

Synced:

• text, as plain text
• links
• pictures, including screenshots, up to 5 MB each
• a single file copied in Finder, up to 200 MB (see Files)

Never synced:

• anything that looks like a password or a key, or comes from an app under Settings › Privacy › Never record copies from (these are not even recorded, see Keep passwords out of your history)
• copies made while Private mode is on
• several files copied at once, folders and apps
• the formatting of formatted text (its plain version is synced)

Files#

Copy one file in Finder, and it is encrypted and uploaded like any other copy. On your other Macs it is downloaded into Downloads › catu and appears in the history as a file copy, with the Mac it came from. Pick it there and paste: into Finder, into an email, anywhere a file goes. catu tells you when a file has arrived.

On the web, a file shows with its name and size. Click it, or its Download button, to save it. To send a file to your Macs from the web, drop it on the box at the bottom of the Clipboard page or click “File…”.

Files take space in your storage while they are in the clipboard, like pictures do. They leave with the item, when newer copies push it out or you delete it.

Your clipboard on the web#

Open your Library and choose Clipboard. The page lists your synced copies, newest first, with the device they came from and how long ago. Pinned items sit on top.

• Click a text item, or its Copy button, to put it on this device’s clipboard. Pictures are copied as PNG. Files download instead.
• Pin keeps an item beyond the last 50. Delete removes it on every device.
• Type the first letters in the search field to narrow the list.

To send something to your Macs, type or paste it in the box at the bottom and press ⌘↩, or drop a picture or a file on it. It arrives in your Macs’ history within half a minute while the catu menu is open, marked as coming from the web.

The first time you open the Clipboard page in a browser, the items show as encrypted. The browser needs your key: see Link a phone or a browser. On the Mac you copied on, choosing “Go to Web Library…” from the catu menu once is enough.

Link a phone or a browser#

The key that opens your clipboard lives only on your devices, so each new device has to be given it once.

1. On a Mac that already has catu, open Settings › Sharing.
2. Under Other devices, click “Link a Phone or Browser…”. A QR code appears with a 6-character code under it.
3. On the phone, scan the QR with the camera and open the link. In a browser, press “Copy Link” and open it there.
4. Type the 6-character code when the page asks for it.

Your Library opens on that device, signed in as you, and your clipboard is readable there. The browser keeps the key in its own storage, so you only do this once per browser. If the browser’s site data is cleared, link it again.

The QR and the link work once and stop working after a minute. The link on its own is useless: whoever has it also needs the code, and the code never leaves the two screens. So you can send the link any way you like, by Messages, AirDrop or email, and read the code out or type it yourself. Still, anyone who has both is signed in as you, so show them only to your own devices.

Link another Mac#

On a second Mac with catu installed, sign in with the same Apple account, then:

1. On the Mac that already syncs, open Settings › Sharing and click “Link a Phone or Browser…”, then “Copy Link”.
2. Send the link to the other Mac any way you like, and note the 6-character code.
3. On the other Mac, open Settings › Sharing and click “Link This Mac to Another Mac…”.
4. Paste the link, type the code and click “Link”.

Both Macs now hold the same key. Turn on “Sync clipboard to catu.app” in Settings › Privacy on the second Mac and its copies join the same clipboard. Copies made on one Mac appear in the other’s history within half a minute while its catu menu is open, marked with the Mac they came from.

If you open the link in a browser on the other Mac instead, the page offers to hand the key to catu there as well.

Share an item as a link#

Any text, link, picture or file in your clipboard can be sent to someone as a catu link, like a screenshot or a recording.

• On the web: hover over the item on the Clipboard page and click the link button, “Share as a link”. Choose how long the link lasts (7 days unless you change it) and whether it needs a password, then click “Create link”. The link is copied for you.
• On your Mac: hover over the item in the catu menu and click the link button. The link lands on your clipboard, ready to paste, and lasts as long as your screenshot links do (Settings › Sharing).

Whoever opens the link sees the text with a Copy text button, the picture, or the file with a Download button. No account is needed, and people can comment. The link appears in your Library like any clip, where you can add or change the password, change the expiry, see views and delete it.

These links are encrypted end to end: the key travels after the # in the link, and catu.app keeps only a locked copy that your own devices can open. So the preview in a chat app shows just that something was shared with catu, not the content.

Privacy#

• Each copy is encrypted on your Mac before it is uploaded, with a key made from an account key kept in your Mac’s keychain. catu.app never receives that key, so nobody at catu can read your clipboard, not even on request.
• catu.app holds only the encrypted items, their size and kind, the device name, the time and whether they are pinned.
• Linking another device hands over the key sealed with both the link and the code, for a minute, once. The server never sees the link’s secret or the code.
• A share link made from a clipboard item is encrypted end to end too: the key is in the link, catu.app holds only copies locked with your clipboard key. Delete the link in your Library and it stops working at once.
• The key sits in your Mac’s keychain. With iCloud Keychain on, Apple carries it to your other Macs, end to end, and a new Mac picks it up by itself; catu still never sees it. Without iCloud Keychain, link a phone or browser so a second device holds it.
• If you lose every device that holds the key, the synced items cannot be recovered. Your local history on each Mac is unaffected.

The full details are in the privacy policy.

Keep a recovery key#

If you don’t use iCloud Keychain, keep a copy of the key yourself: Settings › Sharing › Show Recovery Key shows it right there, as 8 groups of letters and digits, with a Copy button for your password manager. The copy is marked as concealed, so neither catu’s history nor other clipboard managers keep it. Anyone who has the recovery key can read your synced clipboard, so give it to no one.

A new Mac#

Sign in with the same Apple account and turn the setting on. If iCloud Keychain is on, the key is already there and your synced copies open at once. If it is not, catu says the clipboard is locked with a key from another device, and offers to link this Mac to a device that still has it (Settings › Sharing › Link This Mac to Another Mac…, or scan from your phone), to paste your recovery key (Restore from Recovery Key…), or to start fresh, which deletes the old synced copies. Your screenshots, recordings and their links are not affected either way: those keys are kept by catu.app.

Turn it off and delete#

1. Open Settings › Privacy and turn off “Sync clipboard to catu.app”.
2. Choose “Stop and Delete Synced Copies” to remove everything stored on catu.app, or “Stop Syncing” to keep it there.

New copies stay on this Mac. The history already on your Macs is not touched either way. You can also delete everything synced with “Clear all” under the box on the Library’s Clipboard page.

If something doesn't work#

• The Clipboard page says the browser doesn’t hold your key. Choose “Go to Web Library…” from the catu menu on your Mac, or link the browser with the QR and code. Items open as soon as the key is there.
• A copy did not arrive on the other Mac. The other Mac pulls new items while its catu menu is open, and about every half minute after that. Check that “Sync clipboard to catu.app” is on in its Settings › Privacy, and that both Macs are signed in to the same account and linked with the same key.
• The code is refused. Codes and links last a minute and work once. Click “Show a new code” on the first Mac and try again. Letters are not case sensitive.
• Something you copied is not in the web Library. It may have looked like a key, come from a blocked app or been copied in Private mode; those are never synced. A picture over 5 MB, a file over 200 MB, a folder or several files copied together stay on your Mac only. Formatted text arrives as plain text.
• A file did not arrive on the other Mac. Look in Downloads › catu there. Files download when the other Mac next pulls, so a large one can take a moment; pasting works once catu says it has arrived.
• An old item has gone. Only the last 50 items are kept. Pin the ones you want to stay.