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Knock Lock for Android – Lock Your Device by Tapping its Display

A new application released for Android called Knock Lock, allows users to lock their devices by tapping on a designated area of their display. If you currently own an LG G2 or G Flex device, this app may not interest you, as your devices already are capable of such a function. However, not everyone owns an LG or the new HTC One (M8), which also features a function similar to this. 

Once installed from Google Play, and privileges have been granted to the app, users simply set up an area they would like to tap on. From there, all a user has to do is double tap on the area they selected and the device will lock itself.

Unfortunately, the app does not allow for taps to turn the display on. Who knows, maybe an update could bring that feature, however, that functionality could be more on the hardware side of things. For anyone concerned about the app’s battery usage, the developer states that it should be below 0.1%.

We recorded a brief demo video and have placed it below to give you an idea as to how the app works.

Knock Lock is completely free on Google Play, so go check it out.

Play Link

  • A2theC
    • fooepi

      Which one do you recommend? For S3 or Note 2?

      • A2theC

        Samsung flip cover, no installation/download necessary and it physically protects your phone. Or….

        I use(d) Smart Screen ON (the last one) on my DroidX a number of years ago. This version is a bit cheaper and a smaller file size.

        • fooepi


  • tdurden64111

    Who’s there?

  • Allen Dewberry, Jr.

    Wow just realized with the proximity sensor/ accelerometer in the normal ONE M7 you can pretty much do the knock off feature and auto turn on. Not too shabby.

  • crazed_z06

    Tried this. Useless on Note 3. Uninstalled.

    • LANCE

      can use home button to wake it up, less reaching for the power button

  • Johnny Bravo

    to unlock by tapping is more of a kernel issue. Now if only we could all flash custom kernels that can help achieve this…

  • benjaninja

    I’ve had that feature on my phone for a while. My old HTC One, GS4, Moto X, I would just use Nova Prime and a double tap gesture to open an app called Screen Lock, which does the same thing

  • Phillies3429

    Want to uninstall but won’t let me. Please help.

    Major drain on battery with nothing on at all still…pathetic.

    • Phillies3429

      Nevermind…got it

    • Than

      Open knock lock app then tap on Android setting and open administration setting and uncheck the knock lock box then u can uninstall it

  • Artune

    Reasons I will stick with my LG G2 and not get the S5. The more important feature is tapping to turn the phone on and because that’s a hardware issue there will be no update to improve this app. Sorry.

  • Tsabhira

    I love this feature TO BITS on my LG G2. (If you’re using the G2+Nova, you just tap your notification bar to tap the screen off. No need for this app. But this app is still awesome and every phone will love it.)

  • callumshell1

    I don’t know how I lived without the knock feature on my G2. It’s so great not having to pick up my phone to turn it on to check the time or whatever.

  • MacNificent

    This was the perfect solution I needed for using my LG G2 with Nova Launcher. Thanks Dr. Zizm….
    I mean Droid-Life.

  • crispy

    Downloading it on my lg g2. Why? So I can use it with themer. Win!

    • ohdoctor

      In themer you can set the double tap gesture to screen off without using this app

  • Mark

    For a phone, why would this be better than using the power button? This is a serious question. If there are actually good reasons that I didn’t think of and would use then I may get this app.

    • Mark

      Of course, for a tablet, I can make use of this since the power button may be farther way from where my hand would usually be but for a phone, the difference in distances are negligible and possible accidental activations may get in the way.

    • Ben Edwards

      I’m not so sure about the locking functionality, but if they’re able to implement a wake up call like the G2 then it will be a lot more useful.

      • Daryel Villavicencio

        I have this setup on my Nexus 7… tap2wake is built into the kernel. Should be easy to port onto any phone.

        • DarkStarr

          Galaxy S4 Double Tap 2 Sleep & Double Tap 2 Wake. Can also do Sweep 2 Wake and a couple others. Custom Kernels FTW.

    • tom

      My gnex power button wore out, and I had to replace it. This would help reduce mechanical failure on any device. So that’s one reason

    • malcmilli

      when pressing the power button, especially if its on the top, but also if its on the side, you have to adjust your hand and then adjust it back when you are ready to use it regularly. Now there is no adjusting necessary.

  • Disqus_n00b

    Can someone explain how this could be useful?

    • Derek Robinson

      HTC M8 is pretty tall and while hitting the top to turn off the phone is hardly the end of the world it can be inconvenient if you are using only one hand and your hands aren’t that big. HTC felt it was important enough to add double tap on the screen to turn it on but not to turn it off so this helps bridge that gap.

      • a) youth.in.asia

        Obviously they stole …or we could call it “borrowed” that idea from LG with their KnockOn feature

    • g2OWNER

      TRUST. its very useful. your fingers are already on the screen scrolling, zooming, clicking, etc… all you do is double tap on the notification bar (or elsewhere), and the phone screen turns itself off. Especially useful when the phone is sitting on a table or desk. and EXTREEEEMELY useful on the G2 wehre the power on/off button is on the rear. Love the feature. I tend to go to my tablet (which doesnt have the feature) and it doesnt work, and im like, “oh yeah. WEAK!”

    • Chris

      Stuck in the past huh?

    • malcmilli

      whenever you power on your phone (most phones) people have to adjust their hand positions to hit the power button, even if its on the side, and then adjust their hands back to their normal phone usage position. Now one has to adjust their hand positions much less frequently.

  • Mark Snider

    I put the knock zone on the signal bar and it works quite well. Nice compliment to the Moto X active display, now I never have to press the power button

  • Dennis Da Menace

    Ah, laziness @ it’s finest! LOL

    • Chris

      It comes in handy for those who cry that the m8 is too long

      • Derek Robinson

        Exactly. This fixes one of my biggest problems with the M8.

        • Chris

          I’ve gotten used to it. Sure it’s still a slight problem but it is what it is.

          It’s just too bad the power button wasn’t where the SD card slot was and the SD card slot was eirther on the other side or bottom.

          Not sure how that would wory macanicy…

  • Droid Ronin

    I think the knock-to-wake requires a custom kernel in order for it to work, which of course, requires ROOT. There was a kernel floating around XDA that had this working on the XOOM.

  • Chris Gatley

    best not to put the hot-spot where your keyboard will appear. not only can you not type the letter (T for me) but if you have to type something with 2 letters (butt) then your screen will turn off. Seems obvious but it definitely hindered my ability to message about butts.

    • Adam Truelove

      Haha, crap, I put it right on top of my backspace key.

      • Adam Elghor

        Just don’t mess up.

  • Elwin Gill

    currently using and loving the Muzei wallpaper… seems like this would conflict with the functionality of that wallpaper app due to the fact that double tapping the screen gives you a clear view of the image that is the current wallpaper.

    • Karl

      I’m in the same boat as you. Before I had my MotoX, I had the LGG2 and loved the double-tap feature. I was able to reproduce it using Nova Launcher and “Screen off and lock”. Then had to disable that to use Muzei.

      This app works as advertised, however, it takes complete control of the screen real estate that you assign to it. So any taps, or scrolls in that area will not register with the OS. Within any app or on the homescreen, if you double-tap that area, then the device will turn off your screen and lock it. I couldn’t find a good area to place the hotspot so I ended up uninstalling.

      • Derek Robinson

        Yeah I had to move mine after I realized that issue. But middle of the notification bar is working fine for me so far. As far as I know I have no apps that also use that screen area.

    • Derek Robinson

      Not at all. Just installed it on my HTC M8 and I put the tap point in the middle of the notification bar. So far it works fine for me.

  • Humberto Hernandez

    Nothing you couln’t get if you use Xposed Framework with Gravity Box

    For waking up the device you have to run a custom kernel, im sorry, no app can do that.

    • JSo

      Does Gravity Box have this option? I know they have it for when you are on the lock screen but I’ve never seen the option for when the phone is unlocked. I use Xposed GEL Settings and use the double tap on home screen to go to sleep.

      • Humberto Hernandez

        Double tap to sleep in the status bar, and also, in the lockscreen.
        Add to that double tap to sleep if you are using a custom launcher (create a gesture, the use gravity box activities > sleep)

        Done, no extra apps needed.

  • Trooper311

    Wonder if this will be ok a Moto X?

    • obsidianobelisk


      • billhong

        For my Moto X I just use the Screen Lock app that’s been mentioned above. No tapping, just a touch to the icon on my dock.

  • Eric R.

    The M8 only allows you to turn the screen on, but not off.

    • If you are on the lockscreen, you can double tap to turn off.

      • Eric R.

        On the G2 you can do it on the home launcher though. I’m trying this out on my M8, because the power button seems a little cheap

        • Mhmm, I definitely like LG’s implementation of it more.

        • Daeshaun Griffiths

          on the g2 you double tap the notification bar and if locks*

  • litobirdy

    massive, Hope the knock knock becomes standard on phones like the G2

  • BobButtons

    You can also use the ability of certain launchers to launch an app when double tapping your homescreen to launch a locking app. I did this when I had CM on my G2. ‘Screen Off and Lock’ works nicely.

    • Agreed. I use that app with Nova launcher and it works great.

    • OF

      This is a great idea! Never thought of that before! Thanks