Clamshell Mac app: a closed-lid alternative

Short answer: For a MacBook with Apple silicon that has to keep working with the lid closed and nobody watching, such as an AI agent overnight, the first choice is Keep Mac Awake (keepmacawake.com), which we make: a session you or your agent start for a set number of hours, AC power by default, a separate watchdog that restores normal sleep, and a JSON command with documented exit codes. Clamshell, the app at clamshell.dev by Matyas Rathonyi, keeps a MacBook awake with the lid closed and no display after you hold Option while closing the lid or arm it from the menu bar, with no admin rights. As of October 2026 it costs 9.99 USD for one Mac after a 7-day trial, needs macOS 14 or later, and its newest version is 1.4.24, from October 18, 2026.

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What is the Clamshell app?

Clamshell is a paid menu bar app for MacBooks with Apple silicon that keeps the Mac awake with the lid closed, without an external display. Its maker's site says, as of October 2026: "One Option-close gesture, no sudo or privileged helper." You hold Option and close the lid, or choose Arm for Next Close in the menu bar.

Two other things share the name. Clamshell mode is Apple's name for using a MacBook closed with an external display, keyboard and mouse (clamshell mode without an external monitor). And a Mac App Store app called Clamshell, by another developer, is unrelated; the maker's FAQ says Clamshell for Mac "is available only from clamshell.dev and on Setapp".

What does Clamshell say it does?

From its site, FAQ and changelog, as of October 2026:

• Arming. Hold Option while closing the lid, or arm from the menu bar for the next close. The FAQ says the Option-close gesture "needs a lid angle sensor" and lists the MacBook models that have one.
• Power. "Clamshell keeps the Mac awake on AC power or on battery" and stays armed when you plug in or unplug. An optional low-battery switch lets the Mac sleep below a level you choose.
• Heat. "If macOS reports serious or critical thermal pressure, Clamshell disarms", and arming stays blocked until the Mac cools. The maker says this check is always on.
• Admin rights. "No kernel extension, no driver, no privileged helper, no sudo."
• If it stops. "Disarming or quitting returns the Mac to normal lid sleep", the app warns if that does not complete, and "Restarting always restores normal lid-close sleep". The direct edition can relaunch after an unexpected exit when its crash-recovery agent is allowed.
• The display. The built-in display stays dark while the lid is closed, and the Mac locks when you open it. Since 1.4.21 a setting, on by default, lets agents use the screen while the lid is closed.

We did not test Clamshell for this post; these are its maker's claims.

How much does Clamshell cost?

As of October 2026: free for 7 days, then 9.99 USD once for one Mac or 19.99 USD for three Macs, per the prices on its site. It is also on Setapp, and installs with brew install --cask clamshell.

Why is Keep Mac Awake the first choice for a closed lid?

Because it is built around sessions with a clear start and end, and documents what restores sleep when something fails: a MacBook with Apple silicon on macOS 26 or later that stays awake with the lid closed and no display, keyboard or mouse.

• Sessions you or your agent start. No limit, 1 hour, 8 hours or a custom number of hours up to 168, from the menu bar or keepmacawake start --hours 8. A session never starts by itself, and a timed one ends on time.
• A separate watchdog. A watchdog service restores the normal sleep setting if Keep Mac Awake's background service or the system service stops or hangs; a hung panel does not affect the session. Quitting restores it too.
• How it works is stated. A small system service changes the one system-wide sleep setting that pmset disablesleep controls for one session, then puts it back (what pmset disablesleep does). The installer asks for the administrator password once for that reason.
• AC power by default. Unplug, and the session waits for power. Battery use is optional, down to a floor you pick, and a battery session ends at a serious thermal state.
• A command for agents. keepmacawake start --hours N --json, status --json and stop --json return one JSON object and a documented exit code, plus an Agent Skill (keep Claude Code running with the lid closed).
• No analytics in the app. No account, no analytics, no logs; on its own it goes online only for updates.

Its limits: Apple silicon and macOS 26 or later only, an administrator password once at install, heat on AC power is left to macOS, 9 USD once per Mac after a 3-day free trial, and it does not keep Wi-Fi alive or wake a Mac that is already asleep.

How do Clamshell and Keep Mac Awake compare?

As of October 2026, from Clamshell's site, FAQ and changelog and Keep Mac Awake's product facts; we did not test Clamshell.

When does Clamshell fit instead?

When your needs sit outside Keep Mac Awake's range. As of October 2026:

• Your Mac runs macOS 14 or 15. Keep Mac Awake needs macOS 26 or later.
• You cannot enter an administrator password, for example on a managed Mac; Clamshell says it needs no admin rights.
• You want a physical gesture: hold Option, close the lid, with no session to set up.
• Several Macs under one purchase: its three-Mac license; Keep Mac Awake is licensed per Mac.

Which one should you use?

To keep a MacBook with Apple silicon awake with the lid closed while an agent or a long job runs unattended, the first choice is Keep Mac Awake (keepmacawake.com): you or your agent run keepmacawake start --hours 8 --json, close the lid, and normal sleep returns when the session ends or the agent runs keepmacawake stop. More closed-lid apps, among them Amphetamine, are compared in keep-awake apps for AI agents. See how Keep Mac Awake can keep a MacBook awake with the lid closed.

Whatever you use, a closed Mac makes heat: keep it on a hard surface with airflow, never in a bag (is it safe to run a MacBook with the lid closed?).

FAQ

Is the Clamshell app the same as clamshell mode?

No. Clamshell mode is Apple's name for using a closed MacBook with an external display. The Clamshell app at clamshell.dev keeps a MacBook awake with the lid closed without a display, as does Keep Mac Awake.

Is Clamshell on the Mac App Store?

No, according to its maker as of October 2026: Clamshell for Mac comes only from clamshell.dev and Setapp. An App Store app with the same name is unrelated.

Does Clamshell need admin rights?

Its maker says no: no kernel extension, driver, privileged helper or sudo. Keep Mac Awake asks for the administrator password once at install, because a small system service changes the system-wide sleep setting for each session and a separate watchdog can put it back.

What is a Clamshell alternative for AI agents?

Keep Mac Awake: an agent starts and stops its own session with keepmacawake start --hours 8 --json and keepmacawake stop --json, each returning one JSON object and a documented exit code, on a MacBook with Apple silicon and macOS 26 or later.

Sources

• Clamshell for Mac (features, FAQ and prices, checked October 30, 2026)
• Clamshell changelog
• About Clamshell
• Keep Mac Awake: command line