How to block websites on a Mac so you can’t unblock them
Last updated
By Vitalii Kizlov, who makes Cloister. The results below were tested on a MacBook Pro (M1 Pro) running macOS Tahoe 26.
Blocking a website is easy. Keeping it blocked when you want it back is the hard part. Cloister blocks the websites you choose in Safari, Chrome and Firefox until the time you set is up, and once a block starts, nothing in the app ends it early. Here’s how to set one up, and what happens when you try to get out of it.
To follow along, download Cloister. The 14-day trial has nothing withheld.
1. Choose what to block
Cloister blocks lists of websites. Start from one of the seven ready-made lists, Social, News, Video, Shopping, Gaming, Adult and Sports, or make your own: in Cloister’s Settings, under Lists, press +, give it a name, type a site such as example.com, and press Add.
A site you add is blocked with or without www in front, every page of it. Other addresses of the same site, such as m.example.com, go on their own lines, and a single page can’t be blocked on its own. The guides for YouTube and Reddit list the addresses those two use.
2. Start a block
Click the Cloister icon in the menu bar, choose the lists to block, and choose how long, anything from one minute to 24 hours. Press Start session, then Start blocking to confirm. Until the timer ends, those sites won’t open in Safari, Chrome or Firefox.
3. Or let a schedule start it
For the same hours every week, add a schedule: in Settings, under Schedules, press +, pick the lists, the days and the hours, and press Add schedule. It starts the block on its own, even with Cloister closed. A block can include planned breaks, 25 + 5 or 50 + 10, chosen before it starts.
What holds when you try to end it early
There’s no Stop button, by design. The table shows what each usual attempt does to a running session. The first eight were each tried in the middle of a session on a MacBook Pro (M1 Pro) running macOS Tahoe 26, in September and October 2026. The last three are how Cloister is built.
| You try to | What happens |
|---|---|
| Quit Cloister | The block stays. |
| Remove the block by hand, as the Mac’s administrator | It’s back in under a second, as measured. |
| Move the clock forward | The session goes on counting real time. Tested 30 days forward. |
| Tamper with Cloister’s saved session | The block stays, and no longer ends on its own: Cloister leaves it in place and refuses new sessions. |
| Restart the Mac | The session carries on after the restart. Up to ten minutes of the time the Mac was off counts towards it. |
| Switch to Chrome or Firefox, or turn on secure DNS | Still blocked, on 20 September 2026 on macOS Tahoe 26: Chrome with secure DNS set to Cloudflare, and Firefox with DNS over HTTPS at Increased or Max Protection. |
| Use Safari with iCloud Private Relay | Gets past the block until you turn on Cloister’s network filter: allow it in System Settings, and turn it on in Cloister. The filter blocks Safari too. |
| Use a VPN app | Still blocked, on 12 October 2026 on macOS Tahoe 26: Safari, Chrome and Firefox, with a VPN app switched on before the session or during it. |
| Switch Cloister off in Login Items, or stop it another way | Outside a break, the block stays. During a planned break, the sites stay open until Cloister runs again. |
| Ask support to end it | Support can’t. Nothing on a server can. |
| Start the Mac in Recovery mode and remove the block | This works, always. Cloister is a commitment device, not a lock against the Mac’s own administrator. |
Before you start one
Start with a short block. A session you can’t end is only as good as the list you gave it, and you’ll want to fix that list once, not live with it for a day. Leave off what you need for work or school. Planning study evenings? The study guide sets up a term of them on a schedule.
Cold Turkey and Freedom are set side by side with Cloister on the comparison page, including whether each lets a block end early. Coming from SelfControl, Cold Turkey or Freedom? Each has a page on what changes, and how to move: SelfControl, Cold Turkey and Freedom.
Try Cloister on your own Mac
The download is the whole app, with a 14-day trial and nothing withheld. If you buy it and it isn’t for you, there is a 30-day money-back guarantee.
Version 1.0.5 · macOS 15 or later
A separate app · free to download, blocking needs Cloister Pro
How this page was made
The steps follow Cloister for Mac in the app’s own words. The results come from Cloister’s own tests, with the dates given above, except the last three rows, which are how it’s built. If anything here is wrong or out of date, write to support@getcloister.app and it will be corrected.