Knock. Use your iPhone as a password for your Mac.


The Big Ones

  1. Why should I bother locking my Mac?

    Did you know that anyone with access to your Mac can easily see all your saved usernames and passwords in less than 10 seconds without doing anything illegal?

    Leave for 3 minutes to grab a snack and an average person with no technical knowledge can clean out your bank account. Unbelievable, right? This, unfortunately, is just one lonely drop of water in a sea of reasons to keep your Mac locked when you're not around. So if you do just one thing to try and keep your stuff safe, it should be locking your computer.

  2. Is Knock secure?

    Yes, absolutely. Knock doesn't replace your password, and Knock doesn't modify or replace any of your Mac's built in security features. Knock automatically enters your password via a secure, encrypted connection when you knock on your iPhone.

  3. What if someone steals my iPhone?

    If for any reason you can't Knock to unlock your Mac, you can still sign in with your old-fashioned password. If your iPhone is lost or stolen, simply sign in with your password and disable it with one click.


  1. How does Knock work?

    Knock is a pair of apps: one for your iPhone, and one for your Mac. The two apps create a private, secure connection with eachother via Bluetooth Low Energy.

    When you're near your locked computer, Knock for Mac detects your iPhone. After a few security checks, the ring around your avatar pulses green, letting you know your Mac is safe to unlock.

    When you see the green ring light up, knock twice on your iPhone - just like you'd knock on a door - and Knock automatically enters your password.

  2. If my Mac knows my iPhone is there, why do I have to knock?

    In security speak, this is called a Signal of Intent. In regular words, knocking is a natural way to confirm you're ready to unlock your Mac. Since you can knock on your phone even when it's in your pocket or purse, knocking is a super low-effort way of avoiding those embarrassing "oh no what did I leave open on my Mac" moments.

  3. Can I use Knock with more than one Mac?

    Not yet, but soon. :)


  1. What do I need to use Knock?

    To use Knock, you'll need two things:
    1) An iPhone 5S, 5C, 5, or 4S running iOS 7
    2) A Mac that supports Bluetooth Low Energy.

  2. Which Macs support Bluetooth Low Energy?

    MacBook Pro: 2012 or newer.
    MacBook Air: 2011 or newer.
    Mac Mini: 2011 or newer.
    iMac: 2012 or newer.
    Mac Pro: 2013 or newer.

  3. How can I tell which Mac I have?

    The fastest way to tell if your Mac is compatible is to download Knock for Mac. It's free, and we'll let you know if your Mac works with Knock as soon as you open the app.

  4. My Mac isn't compatible. Now what?

    Ugh, sorry about that. If you purchased the iPhone app, you can learn how to request a refund here.

  5. Is Knock compatible with the version of OS X I have installed?

    Knock works beautifully on Apple's OS X Mavericks, a free upgrade for your Mac. Knock also works with OS X 10.8 Mountain Lion, but we wholeheartedly recommend you upgrade to Mavericks.


  1. Is Knock's connection to my Mac encrypted?

    Yep, Knock uses 1024-bit RSA encryption.

  2. What if someone steals my iPhone and my Mac?

    Yikes, talk about a rough day. Even in the case that a thief makes off with both your iPhone and your Mac and is aware that your Mac has Knock installed, you can easily and quickly wipe your iPhone using iCloud to prevent the thief from gaining access to your Mac. (You'll want to do that anyway, even if you don't use Knock.)

  3. What if my iPhone is protected by a passcode or TouchID?

    Knocking on your iPhone will unlock your Mac even if your iPhone is locked.

  4. Can Knock be fooled into giving my password to a malicious application?

    No. Knock verifies the unique code signature of your Mac's login system to make sure only it can access your password.

  5. What if someone near me is also using Knock?

    No worries. Your Mac only recognizes your Knock.

  6. Does Knock use its own proprietary lock screen?

    No. Knock uses Apple's built-in OS X lock screen with our UI on top.

  7. Knock is requesting access to external sites like and Why?

    Our setup process loads a webview for, which includes share buttons that call external APIs.


  1. Does Knock share any information about me?

    No. We hate that stuff too.

  2. Is Knock broadcasting my password everywhere?

    No. That would be, well, quite insecure.

    Knock does broadcast a Bluetooth Low Energy signal, but the signal contains absolutely no personally identifiable information. Before transmitting your password, Knock makes sure it is talking to your Mac. Most importantly, your password is never stored or transmitted in unencrypted form. It is encrypted using industry-standard 1024-bit RSA encryption.

  3. Why does Knock use location services?

    Knock uses 'Significant Location Monitoring', which is a very low-power, low-precision way to watch for big changes in your iPhone's location. Knock does not collect, save, upload or in any way track or share this location information. We use location monitoring to make sure that Knock for iPhone is always on and ready. Knock will still work if you deny location monitoring, but you will need to manually launch the Knock application after you restart your iOS device or if your iPhone closes Knock for any reason. For more information about Significant Location Monitoring, see this guide from Apple.


  1. Knock can't find my iPhone during setup. What should I do?

    Here are a few things to try:

    1. Make sure you've downloaded and opened Knock on both your Mac and your iPhone.
    2. Make sure your iPhone isn't already paired with Knock on another Mac. If it is, unpair your iPhone by pressing on the icon of your Mac and dragging it to the X that appears.
    3. On your iPhone, turn Bluetooth off and then back on.
    4. On your Mac, restart Knock.

  2. Knock doesn't work when I switch to the login window. Why?

    Unfortunately, Knock does not work from the login window, because this feature signs you out of your Mac and prevents your applications from running.

  3. Knock doesn't work when I switch to another account and then switch back to my account. Why?

    Unfortunately, Knock does not work when you sign out of your account, because signing out prevents your applications from running.

  4. Knock doesn't work when I lock my Mac using certain 3rd party apps like Alfred. Why?

    A few 3rd party apps lock your Mac using Apple's Fast User Switching feature, which signs you out of your Mac and takes you to the login screen. Knock does not work when you are signed out of your account, because signing out prevents your applications from running.

    You can easily lock your Mac by clicking the Knock icon in your status bar and selecting "Lock Mac."

  5. Knock doesn't work when I log out of my Mac. Why?

    Unfortunately, Knock does not work when you log out of your account, because logging out prevents your applications from running.

  6. Knock doesn't work the first time I try to unlock after I boot up my Mac. Sup with that?

    When you boot up, you are signed out of your user account. For security reasons, Knock does not work if you are signed out because Apple prevents your applications from running.

  7. I changed my Mac's password, and now Knock doesn't work. What should I do?

    Unlink your phone by clicking the Knock icon in your status bar and selecting Unlink. Then set up Knock again.

  8. Why do I have to move my mouse or touch a key before knocking?

    This is a limitation of the first version of Knock. We'll ship a free update very soon that will solve this issue.


  1. Who's behind Knock?

    William Henderson and Jon Schlossberg make Knock with their bare hands. Not to be confused with bear hands. William is a weird guy who accidentally learned engineering stuff when he was a whippersnapper. Jon learned how to make websites to be better at it than that annoying kid who lived across the street.

  2. you guys know what you're doing?

    We try not to take ourselves too seriously, but we've been around the block a few times. William created a secure mobile payments platform at Square. Prior to that he worked on Mac OS X at Apple. Jon directed the design of an ecommerce system for Bonobos that handles, well, a lot of money. Prior to that he worked on websites like and

  3. Are you hiring?

    Yeah, kinda. We're looking for an exceptionally product-driven engineer to join us as a cofounder.

    You might not trust your product instincts, but you align all of your technical decisions towards making the best possible user experience above all else. We've got no beef with engineers who don't do this-- you just won't jive well with what we're trying to do, and you'd probably find us annoying anyway. But if you're a full stack engineer who leans towards the server and what you really care about is building something people will use and love dozens of times every single day, shoot us an email.

    If you're someone else and you want in on this thing we're doing, we'd still love to chat, but you should probably read this first.

Sorry if we haven't answered your question here. Send us an email, and we'll get back to you straight away.

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