CATLINK Privacy Policy

Update date: May 25, 2026

Effective date: May 25, 2026

Summary

Shanghai Lianchong Intelligent Technology Co., Ltd. (hereinafter collectively referred to as "CATLINK" or "we") is well aware of the importance of personal information to you, and hopes to use this summary to intuitively and concisely introduce to you how we collect, use and protect your personal information. This summary is an overview of the complete privacy policy. If the terms in the main text are inconsistent with this summary, the main text shall prevail.

1. Personal information and device permissions required for our services

(1) Personal information

[Register/Login]

When you register or log in to a CATLINK account, we will collect your mobile phone number or email address, verification code, account ID, and login status information to complete account creation, login, and identity verification. When using the one-tap login function, we will obtain your mobile phone number through the carrier for quick login. When logging in through authorized third-party platforms such as WeChat, AppleID, Facebook, etc., we will obtain the account ID, avatar, nickname and other public information authorized by you after your authorization.

[Device addition and use of pet smart devices]

When you add, bind and use CATLINK smart devices, we will collect your account ID, bound mobile phone number, device serial number, device ID, MAC address, device model, firmware version, device connection status, Wi-Fi name (SSID), BSSID, network type, signal strength, device operation records, device exception logs, and use them to implement device networking, binding, control, status display, firmware upgrades, troubleshooting and security.

[Pet Management Service]

You can upload pet information to create a pet profile, including pet name, avatar, type, breed, gender, age, birthday, weight, multiple pet identities, toileting, eating, drinking, activity and other records, which can be used for pet management, equipment record ownership, trend analysis and reminder services.

[Camera equipment, pictures/videos and cloud storage]

Some CATLINK devices are equipped with cameras, which are mainly used to capture and identify pet life scenes such as pets going to the toilet, eating, drinking, appearing, moving, and equipment abnormalities. Depending on your device model, settings and authorization status, we may process pictures, video clips, event recordings, highlights, shooting times, event types, and pet recognition results captured or generated by the device.

Please pay special attention: CATLINK camera equipment is not designed to monitor people or capture private life content. However, due to factors such as installation location, shooting angle, home environment, presence of visitors, etc., the equipment may capture faces, human bodies, voices, home interior furnishings, minors, visitors, or other private content. You should install the equipment reasonably and provide necessary notification or consent in accordance with the law.

[AI recognition and algorithm optimization]

In order to provide you with functions such as pet identification, toilet identification, eating identification, drinking water identification, multi-pet identification, anomaly detection, picture classification, wonderful moments, smart reminders and other functions, we may automatically analyze device pictures, video clips, pet information, device data, identification results and user feedback to the extent necessary. Subject to your explicit authorization, we may use collected camera pictures, video clips, cloud storage content, and recognition results for algorithm optimization and continuously adjust algorithm effects.

We promise: without explicit authorization, we will not use personally identifiable camera footage for the above algorithm optimization; we will not sell your camera pictures, videos, cloud storage content or private content to third-party companies; we will not provide personally identifiable camera footage to third-party companies for their independent algorithm optimization or other purposes without your separate authorization.

[Customer service, feedback and after-sales]

When you contact us through online customer service, phone, email or feedback channels, we may collect your contact number, email, account ID, nickname, device model, firmware version, device SN, order number, problem description, pictures, videos, voice, chat records, and system logs for handling consultations, complaints, after-sales and troubleshooting.

(2) Device permissions

[Camera/Album Permissions]

Used to scan QR codes to bind devices, upload avatars, submit customer service materials, save or upload device pictures/videos. If you deny permission, you will not be able to use the relevant shooting, uploading, saving and scanning QR code functions.

[Microphone permission]

Used for online customer service voice/video, intercom or sound problem feedback on voice-enabled devices. If you deny permission, you will not be able to use voice interaction, recording and related customer service functions.

[Bluetooth permission]

Used for discovering nearby devices, device distribution, near-field connection, device control and firmware upgrades. Denying permission may prevent you from adding new devices, controlling paired devices, or performing firmware upgrades.

[Location Permission]

Used for Bluetooth or Wi-Fi scanning, nearby device discovery, regional services, nearby service points and other scenarios. Denying permission may affect device discovery, network provisioning, or nearby service functionality.

[Notification push permission]

Used to receive pet events, device status, exception reminders, feeding/drinking/toilet reminders, cloud storage service status, order and activity notifications. After the permission is turned off, you will not be able to receive relevant push notifications.

[Clipboard permissions]

It can only be used immediately when you actively paste the verification code, address, device code and other content. We do not actively read, store or upload your clipboard contents in the background.

2. Personal information sharing and third-party SDK

Unless we obtain your consent or otherwise stipulate in laws and regulations, we will only share and entrust the processing of necessary personal information with affiliated companies, service providers or other partners within the legal, proper and necessary scope. We may share necessary information with Alibaba Cloud, Alipay, WeChat, push service providers, statistical analysis service providers, online customer service providers, mall service providers, etc. to complete functions such as text messages, cloud storage, payment, push, customer service, statistical analysis, mall shopping, etc. You can learn more in the "Third-Party SDK Catalog" attached to this policy.

3. Your personal information rights

You can exercise your rights to inquire, copy, correct, supplement, delete, withdraw authorization, cancel your account, complain and report, etc. through the "System Settings - Account Management" of CATLINK APP, or by contacting us at customer@catlink.cn or customer service hotline (+86) 021-50686520. We will respond to your request within the time limit specified by laws and regulations.

CATLINK Privacy Policy Text

Shanghai Lianchong Intelligent Technology Co., Ltd. (contact address: Room 501, Building C1, Phase 1, Zhangjiang Online New Economic Ecological Park, No. 333 Shengrong Road, Pudong New District, Shanghai) is hereinafter collectively referred to as "CATLINK" or "we" and attaches great importance to the protection of your privacy and personal information. This policy applies to how we process your personal information when you use CATLINK APP, CATLINK Lite, CATLINK smart devices, websites, mini programs, customer service systems and related products or services.

This privacy policy will help you understand the following:

  1. How we collect and use your personal information

  2. How we use cookies and similar technologies

  3. How we entrust processing, share with third parties, transfer, or publicly disclose your personal information

  4. Your rights

  5. Storage of personal information

  6. How we handle minors’ information

  7. Privacy Policy Update

  8. How to contact us

Attachment 1: Third-party SDK directory

1. How we collect and use your personal information

In order to realize the basic functions of providing products and/or services to you, you must authorize us to collect and use necessary information. If you refuse to provide corresponding information, you may not be able to use related functions normally.

1.1 Account registration and login

  1. When you register or log in to a CATLINK account, we will collect your mobile phone number or email address, verification code, account ID, and login status information to complete account creation, login, and identity verification.

  2. If you set a password, we will save your account credentials in encrypted form. Please keep your account number, password, and verification code properly.

  3. If you use the one-tap login function, we will obtain your mobile phone number through the carrier for quick login after obtaining your authorization.

  4. If you choose to log in through a third-party account such as WeChat, AppleID, Facebook, etc., after obtaining your authorization, we will obtain your account identification information, avatar, nickname and other public information authorized by you on the third-party platform to complete account binding and login.

  5. To ensure account security and normal operation, we will also collect login time, login IP address, device model, operating system version, device identifier, network status and other information for account identification, security verification, risk control and system operation.

1.2 Device addition and use of pet smart devices

When you add, bind and use pet smart devices through CATLINK APP, we will collect and use the following information to the extent necessary to achieve device networking, identification, control and service provision:

  1. Account and device identification information: account ID, bound mobile phone number, device serial number, device ID, MAC address, device model, device verification key, firmware version, used to confirm device ownership, identify device uniqueness and ensure device operation safety.

  2. Device networking and configuration information: device connection status, network type, Wi-Fi name (SSID), BSSID, signal strength, IP address, used to complete device networking configuration and connection status judgment. The Wi-Fi and password information you fill in is only used for device network configuration, and we will take security measures such as encryption. Whether to save it locally or upload it depends on the device capabilities and page prompts.

  3. Equipment operation and usage data: equipment online/offline status, battery power, consumable status, fault status, litter box usage records, feeding records, drinking records, weight data, device function usage, used to show you device status, provide pet management, trend analysis, exception reminders and after-sales service.

  4. Device sharing information: If you share your device with family members or other users, we may collect your account ID, the account ID or mobile phone number of the person being shared, the shared device information, sharing permissions, sharing time, and cancellation records for device sharing and permission management.

1.3 Camera equipment, audio, video and interactive data

If you use a CATLINK device with a camera, microphone or voice interaction function, we will process pet-related pictures, videos, voices or event records with your authorization or based on your active use of relevant functions for remote viewing, pet event recording, cloud storage, wonderful moments, intercom interaction, exception reminders and after-sales troubleshooting.

Camera equipment is mainly used to capture scenes such as pets going to the toilet, eating, drinking, appearing, moving, and equipment abnormalities. Due to factors such as the installation location of the device, shooting angle, home environment, presence of visitors, etc., the device may capture faces, human bodies, voices, interior furnishings of the home, minors, visitors or other private content. Please install the device reasonably and avoid pointing the device at bedrooms, bathrooms, dressing areas, other people's private spaces, public passages, neighbor areas or other places that may infringe privacy; if the device is located in multiple people living together, in offices, rentals, foster care, stores, pet hospitals, public or semi-public spaces, you should fulfill the necessary notification obligations in accordance with the law and obtain the consent of relevant persons or their guardians as required by applicable laws.

You hereby clearly understand, agree and authorize us to collect and store all the above-mentioned images including your face, body and other personal information. We promise not to make any active use of this type of information, including but not limited to algorithm training, model optimization or any other form of active processing.

1.4 AI recognition, intelligent analysis and algorithm optimization

In order to provide you with functions such as pet identification, toilet identification, eating identification, drinking water identification, multi-pet identification, anomaly detection, picture classification, wonderful moment generation, intelligent reminders, trend analysis and other functions, we may use the pictures, video clips, pet information, equipment data, sensor data, event records, and recognition results collected by the device to the necessary extent for automated analysis.

AI recognition results may be affected by factors such as light, occlusion, device angle, network status, pet size, coat color, algorithm capabilities, etc., and may include false positives, missed negatives, delays or inaccuracies. They are for your reference only and do not constitute pet medical diagnosis, veterinary advice, home security, emergency alarm or evidence preservation services.

Subject to your explicit authorization, we may use collected camera pictures, video clips, cloud storage content, and recognition results for algorithm optimization, and continuously adjust algorithm effects to improve the accuracy and stability of pet smart device-related functions such as pet appearance, toileting, eating, drinking, multiple pet identities, abnormal behaviors, false positives and omissions, image classification, and highlight moment generation. Relevant authorization should be distinguished from basic device functions and is not a mandatory condition for using basic device functions, except where permitted by laws and regulations.

We promise: without explicit authorization, we will not use personally identifiable camera footage for the above algorithm optimization; we will not sell your camera pictures, videos, cloud storage content or private content to third-party companies; we will not provide personally identifiable camera footage to third-party companies for their independent algorithm optimization or other purposes without your separate authorization. We will take reasonable security measures for the data used for algorithm optimization, and conduct de-identification, anonymization, desensitization, encryption, permission control and access auditing to the extent feasible. You can withdraw relevant authorization through CATLINK APP settings or customer service channels.

1.5 Cloud storage service

When you activate or use the CATLINK cloud storage service, we or our service partners may collect and process pictures, video clips, event recordings, highlights, event lists, recognition results, package types, service periods, order information, upload status, playback records, download records, deletion records, sharing records, error logs, and service status taken or generated by your bound device. The above information is used to achieve cloud storage, cross-device viewing, playback, downloading, deletion, package management, fault handling and security assurance.

The storage period, cycle coverage, expiration cleanup and deletion rules of cloud storage content are subject to the "CATLINK Cloud Storage User Agreement" and the service page display. This document does not adjust the "CATLINK Cloud Storage User Agreement".

1.6 Pet Management

You can upload pet information for creating pet files and managing pets. You may need to fill in your pet's name, avatar, species, breed, gender, age, birthday, weight, sterilization status, multiple pet status, appearance characteristics, toileting records, eating records, drinking records, and activity records. The above information is used for pet file management, multi-pet identification, device record ownership, behavior trends, reminder optimization and after-sales support.

1.7 Store, Orders and Payment

If you use the CATLINK mall or other shopping functions, we may collect the following information based on specific services:

  1. Product display and search: operation records, search content, browsing records/time, used to realize product browsing and search functions.

  2. Add shopping cart: Add shopping cart records for managing shopping lists.

  3. Order placement and order management: order number, product or service information, contact name, mobile phone number, delivery address, transaction amount, payment method, payment status, invoice information, used for identity verification, payment settlement, delivery, after-sales service, order inquiry and transaction security.

  4. Address management: consignee’s name, mobile phone number, location, detailed address, address label, default address settings.

  5. Payment: We usually do not collect your complete bank card number or payment account password directly. Payment services are processed by third-party payment institutions.

1.8 Customer service, feedback, complaints and suggestions

When you contact us through online customer service, phone, email, feedback or complaint suggestion channels, we may collect your contact number, email, account ID, nickname, device model, firmware version, device SN, order number, problem description, pictures, videos, voice, chat records, APP version number, mobile operating system and version, network environment, operation timestamp, which will be used to communicate and verify problems, reply to processing results, locate device problems, query logs, repeat scenarios, and handle transaction disputes.

1.9 Provide you with security

In order to improve the security of the system when you use CATLINK products or services, we may collect log information, click records, browsing records, network diagnosis, lag information, exception logs, device information, device identifiers, IP addresses, network types, operating system versions, application versions, commonly used software information, etc., for account risk judgment, anti-fraud, troubleshooting, security risk control, statistical analysis and service optimization.

1.10 System permissions applied for to implement relevant business functions

  1. Camera permissions and album permissions

  2. Microphone permissions-Business scenarios: voice customer service, video customer service, device intercom, feedback on audio issues

  3. Bluetooth permissions-Business scenarios: adding devices, device network configuration, device control, firmware upgrade

  4. Location permissions

  5. Local network/Wi-Fi permissions

  6. Notification push permission

  7. Clipboard permissions-Business scenario: Actively paste verification code, address, device code

  8. Storage permissions-Business scenarios: save pictures/videos, upload files, read logs

1.11 Other rules for the collection and use of personal information

  1. If we use information for other purposes not specified in this policy, or if we use information collected for specific purposes for other purposes, we will obtain your consent in advance in accordance with the law.

  2. For sensitive personal information, such as faces, human bodies, voices, interiors of homes, images of minors, precise location information, transaction information, identity verification information, etc. that may be captured by cameras, we will only process them with specific purposes and sufficient necessity, and take strict protective measures. In situations where laws and regulations require separate consent, we will obtain your separate consent in accordance with the law.

2. How we use cookies and similar technologies

Cookies and similar device information identification technologies are commonly used technologies on the Internet. When you use our services, we may use cookies, local storage, anonymous identifiers or similar technologies to maintain login status, save preferences, ensure account and transaction security, troubleshoot crashes and delays, statistical analysis and service optimization.

We promise not to use Cookies for any other purpose than those stated in this policy. You can clear or reject cookies through your browser or system settings, but this may cause features that rely on cookies to not work properly.

3. How we entrust processing, share with third parties, transfer, or publicly disclose your personal information

3.1 Entrusted processing

In order to provide you with CATLINK products or services, we may entrust third-party service providers to help us provide operational and service support. During this process, third-party service providers may process your personal information in accordance with our instructions. We will sign a data protection agreement with the entrusted party, requiring it to process personal information only within the agreed purpose, scope and period, and to take protective measures no less than those required by this policy.

3.2 Sharing with third parties

We do not sell any personal information to third parties. We will not sell your camera pictures, videos, cloud storage content, or personally identifiable private content to third-party companies. We will not provide personally identifiable camera footage to third-party companies for their independent algorithm optimization, commercial marketing or purposes unrelated to CATLINK services unless we obtain your separate authorization, are necessary to perform the services you actively choose, and are necessary to comply with laws, regulations or requirements of competent authorities.

Within the legal, legitimate and necessary scope, we may share necessary information with the following types of partners:

  1. SMS service

  2. Cloud services/cloud storage

  3. Payment Services

  4. Push service

  5. Statistics/Crash Analysis

  6. Online customer service

  7. Mall services

3.3 Information transfer

We will not transfer the personal information we collect about you to third parties without your prior consent. However, in the event of a merger, split, dissolution, declaration of bankruptcy, acquisition, asset transfer or reorganization, involving the transfer of personal information, we will inform you of the name and contact information of the recipient, and require the recipient to continue to be bound by this policy. If the receiving party changes the purpose or method of processing, we will require it to obtain your consent again.

3.4 Public disclosure of information

In principle, we will not publicly disclose your personal information. If public disclosure is truly necessary, we will obtain your separate consent or proceed based on the requirements of laws, regulations, judicial agencies, and administrative agencies.

3.5 Situations in which consent is not required by law

In the following circumstances, we do not need to obtain your authorization to process, share, transfer or publicly disclose your personal information:

  1. Necessary to enter into or perform a contract at your request;

  2. Necessary to perform legal duties or legal obligations;

  3. In response to public health emergencies, or when necessary to protect the life, health and property safety of natural persons;

  4. Implement news reporting, public opinion supervision and other activities for the public interest, and process personal information within a reasonable scope;

  5. Process personal information that you disclose yourself or that has been legally disclosed by others within a reasonable scope;

  6. Other situations stipulated by laws and regulations.

4. Your rights

You can view and manage your information in the following ways, and we will respond to your request in compliance with legal and regulatory requirements.

4.1 Query, correct and supplement your personal information

You can query, correct, and supplement your personal information through the account information, pet files, device management, address management and other pages of CATLINK APP. If you are unable to operate through the aforementioned paths, you can contact us through the methods listed in "How to Contact Us" in this policy.

4.2 Copying your personal information

You have the right to obtain a copy of your personal information. You can make a request through the method listed in "How to Contact Us" in this policy. Subject to relevant legal requirements and technical feasibility, we will provide you with a copy of your personal information according to your request.

4.3 Delete your personal information

You have the right to request the deletion of your personal information under the following circumstances:

  1. We will no longer provide products or services to you;

  2. We have no legal basis to process your personal information, or you withdraw your consent;

  3. We process personal information in violation of laws and regulations or our agreement with you;

  4. You cancel your account;

  5. Other situations stipulated by laws and regulations.

4.4 Close your account

If you wish to cancel your CATLINK account, you can submit a cancellation application through "System Settings - Account Management - Cancel Account" on the CATLINK APP, or contact us through the methods listed in "How to Contact Us" in this policy. After you cancel your account, we will delete or anonymize your personal information, unless otherwise provided by laws and regulations. After canceling your account, you may not be able to continue to use the full range of CATLINK products and services. Mall orders, cloud service data, smart device data, members, coupons, etc. related to your account may not be retrieved or restored, so please operate with caution.

4.5 Withdrawal of consent

You can withdraw your previously given authorization consent through CATLINK APP settings, system permission settings or contact us. Withdrawal of consent will not affect the personal information processing activities that were carried out based on your consent before the withdrawal. For authorization related to algorithm optimization, you can withdraw it through APP settings or customer service channels; after withdrawal, we will stop using your identifiable data for corresponding algorithm optimization purposes, unless otherwise provided by laws and regulations or the data has been anonymized and cannot identify specific individuals.

4.6 Responding to your requests

For security reasons, we may need to verify your identity. Under normal circumstances, we will respond to processing opinions or results within fifteen working days or within the time limit specified by laws and regulations. We may reject requests that are unreasonably repetitive, require excessive technical means, pose risks to the legitimate rights and interests of others, or are extremely impractical in accordance with the law.

5. Storage of personal information

5.1 Personal information storage period

We will retain your personal information for the reasonable and necessary period required to achieve the processing purposes described in this policy, unless otherwise provided by laws and regulations or as otherwise authorized by you. After the storage period has expired, we will delete or anonymize your personal information in accordance with applicable legal requirements.

When determining the specific storage period, we usually consider the following factors:

  1. The necessary period to ensure the operation and security of the CATLINK account;

  2. The necessary period required for the smooth fulfillment of orders, after-sales and customer service support;

  3. The necessary time limit required to meet financial audit, tax declaration and other requirements;

  4. Laws and regulations stipulate the storage period of personal information, such as network logs should be no less than six months, and transaction information should be no less than three years from the date of completion of the transaction;

  5. The storage period required in accordance with the law’s statute of limitations or to cooperate with government department investigations;

  6. The storage period separately agreed between us and you.

Pictures, video clips, event recordings, highlights and recognition results captured or generated by the device will be saved, overwritten or deleted according to your device settings, cloud storage package, retention period, cycle override rules, active deletion operations or service expiration rules.

Data used for algorithm optimization and algorithm effect adjustment will be saved and used within the scope of your authorization. When you withdraw your authorization or the relevant processing purposes are no longer needed, we will stop using your identifiable data for corresponding algorithm optimization purposes, and delete, anonymize or obtain additional authorization in accordance with the law; unless otherwise provided by laws and regulations or the relevant data has been anonymized and cannot identify a specific individual.

5.2 Where personal information is stored

In principle, the personal information we collect and generate in mainland China will be stored in mainland China. If cross-border transfer is required for business, we will provide your personal information to overseas entities after fulfilling our obligations under the law and obtaining your separate consent, and ensure through contractual agreements and other means that the overseas recipient protects your personal information to a level no less than stipulated in this policy.

5.3 Personal Information Security

We will take reasonable and feasible security protection measures that are in line with industry standards and ensure the security of your personal information from both technical and organizational management aspects to prevent your personal information from being modified, accessed, disclosed, used or deleted without authorization. Relevant measures include encrypted transmission, access control, permission classification, log auditing, data desensitization, employee confidentiality obligations, supplier security assessment and security incident emergency response.

If a personal information security incident occurs, we will take appropriate and necessary disposal measures in accordance with legal and regulatory requirements, and inform you and report to regulatory authorities in accordance with the law.

6. How we handle minors’ information

Our products, websites and services are primarily intended for adults. If you are a minor, you should use our products or services with the consent and guidance of your parents or other guardians.

If a CATLINK smart device may photograph minors, the device owner, manager or guardian should ensure that it has legal, legitimate and necessary purposes of use, and obtain the necessary consent from the guardian in accordance with the law. Guardians should reasonably manage minors’ use of CATLINK APP, equipment, camera content, cloud storage, sharing functions and paid services.

If we find that the personal information of minors has been processed without the consent of the guardian, we will delete it as soon as possible or take other necessary measures in accordance with the law. Guardians can contact us through the methods listed in this policy to request inquiries, corrections, deletions, copies of minors' personal information, or the withdrawal of relevant authorizations.

7. Privacy Policy Update

We may revise this policy from time to time. If there are major changes to this policy, we will notify you through APP pop-ups, prominent page prompts, announcements, text messages, emails or other reasonable means, and will obtain your consent again when required by laws and regulations.

Your continued access, browsing and/or use of CATLINK products or services from the effective date of the revision of this policy will be deemed to have fully understood and agreed to the revised policy.

8. How to contact us

Company name: Shanghai Lianchong Intelligent Technology Co., Ltd.

Contact address: Room 501, Building C1, Phase 1, Zhangjiang Online New Economic Ecological Park, No. 333 Shengrong Road, Pudong New District, Shanghai

Contact number: (+86) 021-50686520

Customer service email: customer@catlink.cn

Contact information of the person in charge of personal information protection: customer@catlink.cn (please indicate "personal information protection")

If you have any questions about this policy, or your personal information rights and interests are affected, you can contact us through the customer service in CATLINK APP, customer service phone number or customer service email. Normally, we will respond within fifteen working days.

Attachment 1: Third-party SDK directory

In order to provide and optimize our services, CATLINK APP has embedded third-party SDK. These SDKs may collect your personal information when cooperating with us to provide services. The following is the SDK directory compiled based on the existing CATLINK policy. Before going online, please check again with the actual integrated version of the APP, the latest privacy policy of the SDK, and the permission call status.

  1. SDK name: WeChat Open Platform SDK

  2. SDK name: QQ Sharing SDK

  3. SDK name: Weibo/Sina SDK

  4. SDK name: Bugly

  5. SDK name: Umeng SDK

  6. SDK name: Huawei Push

  7. SDK name: Xiaomi Push SDK

  8. SDK name: OPPO push SDK

  9. SDK name: Aurora Push SDK

  10. SDK name: Aurora Security Certification SDK

  11. SDK name: Tencent senseless login SDK, China Telecom SDK

  12. SDK name: Tencent Browser/X5 SDK

  13. SDK name: Amap SDK

  14. SDK name: Alibaba Cloud Video SDK

  15. SDK name: Alibaba Cloud SDK

  16. SDK name: Alipay SDK

  17. SDK name: Weidian SDK

  18. SDK name: MobTech ShareSDK

  19. SDK name: NetEase Qiyu SDK

  20. SDK name: NetEase Yunxin SDK