Lok – User’s Manual

Lok is an app created by an ex-Facebook engineer to solve a simple, yet persistent issue in social networking apps today: data security and privacy. Our permanently-free app enables you to intuitively and safely connect with those you care most about in a focused way. Unlock day-to-day productivity enhancements with innovative features such as location-based notifications including to-do lists, events, chats, and albums.

Lok does all of the above with best-in-class security and privacy: the app encrypts all your texts and media using the Advanced Encryption Standard (AES) algorithm and a password that only you possess.

Download it today

Why This App?

Tech giants are peeking into everyone’s privacy. The world needs an app that lets people communicate with their loved ones privately and securely on their own terms.

Lok does this by encrypting all the texts and media within each social circle with a circle-specific password, which makes that communication chain impossible to access without the password. This eliminates the possibility of anyone else outside of your approved group peeking into your data – even the folks on the Lok team.






Search for “Lok” on App Store, or
use this download link.

App Store



Search for “Lok” on Google Play Store, or
use this download link.

Google Play

Hate annoying app notifications that add zero value to your day?

We have none of those – so make sure to enable the recommended notifications when prompted to unlock all of our functionality!

Account Management



Click “CREATE AN ACCOUNT” at the bottom and you will be guided step-by-step to create your account using your cell phone. Please be aware that if you don’t receive the verification code, please check if you blocked the sender (650) 409-9686. Contact us support@k8sllc.com if you have problems.

Profile Customization

Use the bottom-right button to go to the settings page, where you can modify your name, email, profile picture, etc.


Circle / Family Management

We support two types of social circles: “Circles” for friends and activities, and “Families” for families. Currently, they have the same functionalities but in the future this may change.


Create Circle / Family

Every normal user can create up to 5 circles / families. VIP users can create more than 100.

Use the bottom-right button to create a circle / family. During creation, there are two ways to provide the password. You can either provide a strong password by yourself, or use the “Generate strong password” button to generate a new one on your phone (ONLY ON YOUR PHONE). When a new password is generated, please make sure to save it in a secure location since we cannot recover it if you lose.

We NEVER store your circle password! We store a random secret and the encrypted value using your circle password and the AES algorithm, and will use them for password validation. Hypothetically, if a hacker compromises our whole database and cloud files, they still won’t see your circle contents, including all texts and images, until

  1. The user personally approves them to join the circle, and
  2. They know the actual circle password. Therefore, please carefully store your circle password!

Share Circle / Family

In the circle / family, you can use the menu to display or export a QR code. Other members would have to scan this QR code to join your circle / family.


Join Circle / Family

Use the bottom-right button to scan and join the family. You will be prompted to verify the password. If the verification passes, the circle creator will receive a push notification. They can then approve the joining request.

Note in this verification step, the circle password is not transmitted online!

Export Locally-cached Passwords

In the settings menu, you can export locally-cached passwords if you have provided them after logging in. Note this will only be available after you entered the circle passwords.


Family / Circle Features

Note for all features: on the top-right of every page, we provide an encryption toggle that allows you to see how your data is stored on the server.


Jointly manage tasks with a synchronized to-do list for your circle.

Create to-do

Tap the top-right “+” icon.      


Edit to-do

Tap the to-do item.                               


Status change

tap the button on the left of a to-do item.


Delete a to-do

left swipe on a to-do item, then tap delete.


Re-order to-dos

press and hold a to-do item, then drag.



Coordinate circle-specific events with a shared events list. Not a hassle to use, as events are automatically synchronized to your device. On iOS it is synchronized to the “Home” calendar on your iCloud account. You can update images for an event, which will be encrypted. You can add locations to events.

Create a new event

Tap the top-right “+” icon and follow the prompts. You can set event titles, start/end dates and times, make the event a recurrence, and insert a description.


Edit upcoming events

On the main Events page, tap the event you want to edit and navigate through the prompts. View past events: on the main Events page, tap “Past”.                        


Accept an event

Tap the upcoming event (either “unread” or “pending”), and tap the “Accept” button. The accepted event will then show “Accepted” in your upcoming event list.                        


Decline an event

Tap the upcoming event (either “unread” or “pending”), and tap the “Decline” button. The declined event will then show “Declined” in your upcoming event list.                        



Chat with your family or circle mates: enter text into the “Type your message” field and hit the blue send button. This will be sent to all members of your family or circle.

Add people to your family or circle

Tap the “+” button on the top-right of the page to get a QR code to share.


Edit a message

Long-press the message and select Edit.


Delete a message

Long-press the message and select Delete.


Copy a message

Long-press the message and select Copy.



Everyone loves a photobook.

Create an album

Tap the upper right “+” button to create an album and use the “Add Photos” and “Upload” buttons on the bottom of the screen to add content.


Delete and album

Long-press an album.


Move images / albums

Long-press the images, select, and then click the move button to select the destination.


Delete images

Long-press the images, select, and then click the delete button.


Logs & more




Keep track of who does what in your circles.



Manage additional Circle or Family features on this page, such as members, share your QR code, delete the Circle/Family, or update the Circle/Family name.



Change Password


Change phone number


Privacy Policy


Terms of Use


Clear Cache


We cache images to local storage for faster image loading. Use this item to clear your local cache to save local space. It won’t affect the locally-cached passwords.

Locally-cached passwords


The password you input for each circle / family is stored locally. Use this feature to copy them to clipboard or export to images.



We support American English, Chinese (simplified and traditional), and Japanese.


Dark mode

System / Light / Dark



  • Why do you use the password-based AES symmetric encryption instead of an asymmetric encryption?

    It is possible to use an asymmetric encryption. However, there are 3 challenges:

    1. The asymmetric encryption is much slower than the symmetric encryption;
    2. We will need to govern the key exchanges so every client can get the public keys off all other clients, which introduces possibilities of man-in-the-middle attacks in case our code is imperfect; and
    3. The clients will be responsible to back up their own private keys, which is even harder than backing up their passwords.
  • How do I recover the contents if I lose my cell phone?

    All the contents in our app are backed up in the cloud. If you lose your cell phone, you can still use the original personal phone number and password to login. You will need to type in the circle / family passwords to unlock them and their contents.

  • What do you store on your servers?

    All information you can see in the App is encrypted before it is stored on our servers so the app will never store your data in a readable way. In your circles, you can use the “On server” toggle on the top-right to see which information is encrypted and which is not.
  • How do I back up my circle/family password?

    All the contents in our app are backed up in the cloud. If you lose your cell phone, you can still use the original personal phone number and password to login. You will need to type in the circle / family passwords to unlock them and their contents.