Second Display Support
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Topics
- Which Macs work iMacs and MacBooks that can be a display, and what macOS offers on its own. 4 articles
- Get started Set up both Macs, choose their roles and allow what macOS asks for. 6 articles
- Cables and connections Thunderbolt and the ⚡︎ ports, a USB‑C cable, Wi‑Fi and Ethernet. 3 articles
- Picture and quality Quality levels, the speed test, resolution, colour and the live statistics. 6 articles
- Everyday use Arrange displays, use several of them, sleep, updates. 7 articles
- Trial, licence and account The free trial, buying, your licence and your account. 6 articles
- Privacy How your screen travels and what Second Display records. 2 articles
- Troubleshooting Cable messages, a Mac that isn’t found, a pulled cable and more. 7 articles
- Contact support Write to us and a person will answer. Email
All articles
Which Macs work
- Target Display Mode and newer iMacsTarget Display Mode works only on some iMacs from 2009 to mid 2014. Second Display turns iMacs from late 2015 on into a display for the Mac you work on.
- Which iMacs can be a displayAny iMac that runs macOS 12.3 or later can be a display for your Mac: the models from late 2015 on, up to iMac with Apple silicon. What each one needs.
- Use a MacBook or another Mac as a displayAny Mac with macOS 12.3 or later can be a display for the Mac you work on, a MacBook too. How to set it up, and what happens on battery.
- AirPlay, Sidecar and Universal ControlAirPlay, Sidecar and Universal Control come with macOS. What each one does, and when Second Display is the better fit for an iMac.
Get started
- What you needTwo Macs: the one you work on with macOS 14 or later, and one to use as a display with macOS 12.3 or later, joined by a Thunderbolt cable or the same network.
- Set up Second Display on both MacsOpen the app on both Macs, choose a role on each, plug in the cable and follow the steps on the Mac you work on. It takes about a minute.
- Computer and Display: the two rolesEach Mac runs Second Display in one of two roles: Computer on the Mac you work on, Display on the Mac you use as a screen. You can switch later in Settings.
- Allow Screen RecordingSecond Display needs Screen Recording on the Mac you work on to show its screen on the other Mac. The display Mac never asks for it.
- Allow Local Network accessOn macOS 15 and later, macOS asks each Mac once whether Second Display may find devices on your local network. Allow it on both: the cable needs it too.
- Open Second Display at loginSecond Display can open by itself when you log in, so a display Mac is ready after every restart. It works from the Applications folder.
Cables and connections
- Thunderbolt: which cable and which port?For the lossless picture, use a Thunderbolt cable, such as a Thunderbolt 4 cable, in a port with the ⚡︎ symbol on each Mac.
- A USB‑C cable without ThunderboltA USB‑C cable that isn’t Thunderbolt, or a port without the ⚡︎ symbol, can still connect the two Macs: the picture continues over USB, compressed.
- Use Wi‑Fi or EthernetWithout a cable, Second Display works over Wi‑Fi or Ethernet with a compressed picture. Keep both Macs on the same network, one you trust.
Picture and quality
- Quality levels and the speed testSecond Display has four quality levels: Low, Medium, High and Highest. A speed test of about five seconds recommends one, and you can choose another at any time.
- The statistics line and Check SmoothnessUnder each display in the menu, a live line shows the stream, the frame rate and the delay, for example “Raw · 60 fps · 9 ms”.
- Larger text or more spaceChoose Larger Text, Default or More Space for each display, in the menu or in Settings › Display. Each choice shows the size it looks like.
- What “about 9 ms” meansAbout 9 ms is the median latency: the time from capturing a frame on the Mac you work on to that frame being ready on the iMac, over a Thunderbolt cable.
- ColourOver Thunderbolt, colours come through exactly: we measured a mean colour difference of 0.14 on grey test patches. For fine coloured lines there is Full colour.
- Older Macs and Intel iMacsAny Mac with macOS 12.3 or later can be the display, with Intel or Apple silicon. The speed test finds the best quality the two Macs can keep up.
Everyday use
- Arrange your displaysPlace the iMac next to your Mac in System Settings › Displays, as with any display. Second Display remembers where you put it.
- Use several displaysOne Mac can drive several displays at once. Add each one with Add Display…; each keeps its own quality, resolution and position.
- Show several Macs on one iMacSeveral Macs can show their screens on one iMac at the same time. Each gets its own window, side by side, and any of them can go full screen.
- Sleep, wake and the lock screenWhile it waits, the display Mac’s screen sleeps like a monitor’s and wakes when your Mac connects. While a picture is shown, both Macs stay awake.
- Get back to the iMac’s own desktopWhile it shows a picture, the iMac has no controls over it. Turn the display off from your Mac, or quit Second Display on the iMac.
- Keyboard, mouse and soundIn this version the iMac’s keyboard, mouse and speakers aren’t used. Work with the keyboard and trackpad of the Mac you work on; sound plays there too.
- UpdatesSecond Display checks for updates by itself, and every future update is included with your licence.
Trial, licence and account
- The free trialThe 7-day free trial starts the first time you sign in. It needs no payment details.
- Sign in and your accountYou sign in only on the Mac you work on: with a 6-digit code sent to your email, with Apple or with Google. The Mac you use as a display needs no account.
- Buy Second DisplaySecond Display costs $39, paid once, with every future update. You buy it on this website, and the licence belongs to your account.
- Your licence on other Macs and offlineYour licence belongs to your account: sign in with it on every Mac you own or control. Second Display works offline for up to 30 days at a time.
- RefundsIf Second Display doesn’t work for you, write to support within 14 days of your purchase and we’ll refund the full price.
- Delete your accountYou can delete your account on the account page. Every Mac is signed out, and a licence is lost with the account.
Privacy
- How your screen travelsThe picture goes straight from one Mac to the other, over your cable or your local network, and never through our servers. It isn’t encrypted.
- What Second Display recordsThe app records product events without personal data, keeps its logs on your Mac, and sends diagnostics only when you send them yourself.
Troubleshooting
- Thunderbolt didn’t connect: the cable messagesIf the cable doesn’t come up as Thunderbolt, Second Display says what it sees. Here’s what each message means and what to do.
- If the other Mac isn’t foundWhen setup says “Your other Mac wasn’t found”, or the menu says the iMac wasn’t found, check these in order.
- The cable was unplugged: Continue over Wi‑FiPulling the cable ends the session. Plug it back in to reconnect, or click Continue over Wi‑Fi to keep going without it.
- The picture stutters over Wi‑FiWi‑Fi has short stalls that a cable doesn’t. These steps usually help.
- What the status messages meanThe line under each display in the menu says what Second Display is doing. Here’s what the less obvious ones mean.
- Send diagnosticsIf something goes wrong, export diagnostics from Settings › Advanced and attach the file to your email. Each Mac exports its own.
- Contact supportWrite to us and a person answers. Here’s what helps us help you quickly.
Still need help?
Write to us and a person will answer. Attach diagnostics if something isn’t working.