Privacy Policy

Knowcall ("the App", "we", "us", "our"), operated by Tranquil Mind Technology JSC, respects your privacy. This Privacy Policy explains what information we collect, how we use and share it, and the choices and rights you have. By using the App, you agree to this Policy.

Knowcall is a caller-identification and call-screening utility for Android: it matches incoming and searched phone numbers against the contacts saved on your device, lets you build your own spam and block lists, and keeps a local log of message notifications you have not yet seen. You do not need to create an account to use it, and Knowcall does not operate a server of its own.

1. Information we collect

1.1 Information that stays on your device and is never sent to us

This is the most important part of this Policy. Knowcall has no backend server. The following information is read and stored only on your device, in the App's private storage, and is never transmitted to us or to any third party:

• Your contacts. With your permission, Knowcall reads the contacts stored on your device so that a saved number can be displayed with a name instead of a bare number, and so the Contacts and Call tabs can list and dial them. Your contact list is not uploaded anywhere.
• Your spam list and block list. The phone numbers you add are stored in local application preferences and mirrored to a local native preference file so the call-screening service can read them while the App is closed.
• Your lookup history. Numbers you type into the Tracker tab, and the result of each lookup, are saved locally.
• Message notifications ("Unseen"). If you grant notification access, Knowcall records the app name, title and text of message notifications delivered to your device so you can read them later, and stores them locally. This log never leaves the device.
• Your settings. Language, theme, toggles and similar preferences.

You can erase all of this at any time by clearing the App's storage in your device settings or by uninstalling the App. Revoking the contacts permission or notification access in system settings stops the corresponding collection immediately.

1.2 Information collected automatically by third-party services

Knowcall includes third-party software development kits for advertising, analytics, crash reporting and payments. These SDKs collect and transmit the following off your device:

We do not collect your name, email address, postal address, phone number, photos, camera or microphone input, precise location, SMS messages, or call logs. Knowcall requests no SMS permission and no call-log permission.

2. How we use information

• To provide and operate the App — display caller names from your contacts, screen calls against your lists, and show your unseen-message log. This processing happens on your device.
• To show advertising — Knowcall is free and supported by ads. Advertising identifiers, IP-derived approximate location and app-activity signals are used by our advertising partners to select and measure ads, including personalized ads where you have consented.
• To measure and improve the App — aggregated analytics tell us which features are used so we can prioritise work.
• To diagnose problems — crash logs and diagnostics help us find and fix defects.
• To prevent fraud and abuse — our advertising and attribution partners use identifiers to detect invalid traffic and attribution fraud.
• To process purchases — if you buy an optional subscription, Google Play processes the payment and reports the purchase status to the App so the entitlement can be applied.
• To comply with law — where we are legally required to retain or disclose information.

3. Third-party services

Each of the following services processes data as described above and under its own privacy policy. We encourage you to read them.

Advertising consent (EEA, UK and Switzerland)

When you are located in the European Economic Area, the United Kingdom or Switzerland, Knowcall presents a consent message on first launch using Google's User Messaging Platform, in accordance with the IAB Transparency and Consent Framework. Your choice determines whether our advertising partners may use your data for personalized advertising. You can change your choice at any time through the privacy options available in the App.

Resetting or opting out of your advertising ID

Android lets you control the advertising identifier that our partners use. Open Settings → Privacy → Ads (the exact path varies by device and Android version) and choose Reset advertising ID to break the link to past activity, or Delete advertising ID to stop apps from receiving one at all. You will still see ads, but they will be less relevant.

4. How we share information

We do not sell your personal information for money. We share information only as follows:

• With the third-party services listed in Section 3, for the purposes described there. Advertising and mediation partners act as independent controllers of the identifiers and signals they receive and use them for their own advertising purposes.
• For legal reasons — to comply with a law, regulation, legal process or enforceable governmental request; to enforce our Terms of Service; or to protect the rights, property or safety of our users, the public or us.
• In a business transfer — if we are involved in a merger, acquisition, financing or sale of assets, information may be transferred as part of that transaction, subject to this Policy.

Notice for residents of California and other U.S. states. Under laws such as the California Consumer Privacy Act as amended by the CPRA, the use of advertising identifiers for personalized advertising may be treated as a "sale" or "sharing" of personal information, or as "targeted advertising", even though no money changes hands. You may opt out at any time by declining personalized advertising in the App's consent options, by resetting or deleting your advertising ID as described in Section 3, or by contacting us at contact@tranquilmind.co. We will not discriminate against you for exercising this right.

We never share your contacts, your spam or block lists, your lookup history, or your unseen-message log — those never leave your device in the first place.

5. Legal bases for processing (EEA and UK — GDPR)

• Consent (Article 6(1)(a)) — personalized advertising, and analytics where consent is required in your jurisdiction. You may withdraw consent at any time through the App's privacy options.
• Legitimate interests (Article 6(1)(f)) — operating and securing the App, non-personalized advertising, crash reporting, fraud prevention and product improvement, balanced against your rights and freedoms.
• Performance of a contract (Article 6(1)(b)) — delivering an optional subscription you have purchased.
• Legal obligation (Article 6(1)(c)) — retaining transaction records and responding to lawful requests.

6. Data retention

• Information stored on your device (Section 1.1) is kept until you delete it in the App, clear the App's storage, or uninstall the App. We cannot access or delete it for you, because we never receive it.
• Analytics and advertising data is retained by our partners under their own retention schedules; Google Analytics for Firebase event data is retained for a limited period configured in our Firebase project, and identifiers are retained by advertising partners under their policies.
• Crash logs and diagnostics are retained for a limited period sufficient to diagnose and fix the underlying defect.
• Purchase records are retained as long as required to support the entitlement and to meet tax and accounting obligations.

7. Your rights

7.1 EEA, UK and Switzerland (GDPR / UK GDPR)

You have the right to access your personal data; to have inaccurate data corrected; to have your data erased; to restrict or object to processing, including profiling for direct marketing; to data portability; to withdraw consent at any time without affecting the lawfulness of processing before withdrawal; and to lodge a complaint with your national supervisory authority.

7.2 California and other U.S. states (CCPA / CPRA and equivalents)

You have the right to know what personal information is collected, used and disclosed; to delete personal information; to correct inaccurate personal information; to opt out of the sale or sharing of personal information and of targeted advertising; to limit the use of sensitive personal information; and not to be discriminated against for exercising these rights. Knowcall does not knowingly collect sensitive personal information.

7.3 Other regions

Residents of Brazil (LGPD), Canada (PIPEDA), Australia, Japan, South Korea and other jurisdictions have comparable rights of access, correction, deletion and objection under their local laws. We honour those requests on the same terms.

7.4 How to exercise your rights

Email contact@tranquilmind.co with the subject line "Privacy request".

Because Knowcall has no accounts and no server, we cannot identify you from a name or email address. To let us locate any data held about you by our partners, please include in your request:

• your advertising ID (Android Settings → Privacy → Ads shows it, where available),
• your device model and Android version, and
• the approximate date you first installed the App.

We will respond within the period required by applicable law — 30 days under the GDPR and 45 days under the CCPA, each extendable where the law permits. Where the data is held solely by a third-party partner, we will forward your request to that partner and tell you we have done so.

You can also delete everything the App holds locally at any time, without contacting us, by clearing the App's storage or uninstalling it.

8. Children's privacy and Child Safety Standards

Knowcall is intended for users aged 16 and over, or the higher age of digital consent that applies where you live. It is not directed to children, is not designed to appeal to children, and is not distributed through Google Play's Designed for Families programme.

We do not knowingly collect personal information from children under 13 (or under the applicable age of digital consent in the EEA and the UK, which is between 13 and 16 depending on the country). If you believe a child has provided information to us or to one of our partners through the App, contact contact@tranquilmind.co and we will take steps to have it deleted.

8.1 Child Safety Standards (CSAE)

These are the published Child Safety Standards of Knowcall, developed and operated by Tranquil Mind Technology JSC, adopted in alignment with the Google Play Child Safety Standards policy.

Zero tolerance for child sexual abuse and exploitation. We prohibit, without exception, child sexual abuse material and any child sexual abuse or exploitation ("CSAE") in connection with Knowcall. This prohibition covers images, video, audio, text and artificially or AI-generated material, and it applies to: the sexualization of minors; the grooming, solicitation, sextortion or trafficking of minors; and any attempt to create, request, access, store, share, promote or facilitate access to such material. There is no context in which this content is acceptable.

How Knowcall is designed to prevent it. Knowcall does not host, transmit or publish any user-generated content. It provides no chat, no comments, no user profiles, no user-to-user messaging and no way for one user to send content to another. All content the App displays — your contacts, your own spam and block lists, and message notifications delivered to your own device by other applications — is read and stored locally on your device and is never uploaded to us or made visible to anyone else. There is therefore no surface within Knowcall through which CSAE material can be shared, distributed or discovered, and no user-generated content for us to moderate.

Reporting and response. If you encounter anything relating to child safety in connection with Knowcall, contact our child-safety point of contact at contact@tranquilmind.co. We review every report we receive. Where a report concerns apparent child sexual abuse material, we will report it to the National Center for Missing & Exploited Children (NCMEC) at https://report.cybertip.org and, where required or appropriate, to the competent authorities in Vietnam and in the relevant jurisdiction, and we will preserve the related information as the law requires. Where we identify a user misusing the App in violation of these standards, we will terminate their access. Suspected child sexual abuse or exploitation occurring outside the App should be reported directly to your local law enforcement authority; in an emergency, contact emergency services first.

Compliance. We comply with applicable child-safety laws in the jurisdictions where Knowcall is distributed, and we review these standards whenever the App's functionality changes. Should Knowcall ever introduce a feature allowing users to communicate with one another or to publish content, we will implement content standards, proactive and reactive moderation, and an in-app reporting mechanism before that feature is released, and we will update these standards accordingly.

Child-safety point of contact: contact@tranquilmind.co

9. International data transfers

Tranquil Mind Technology JSC is based in Vietnam. The third-party services listed in Section 3 process data on servers in the United States, the European Union and other countries, which may have data-protection laws different from those in your country. Where personal data of individuals in the EEA or the UK is transferred outside those areas, our partners rely on appropriate safeguards, including the European Commission's Standard Contractual Clauses and the UK International Data Transfer Addendum, or on an adequacy decision.

10. Data security

Data transmitted by the third-party SDKs described in this Policy is encrypted in transit using HTTPS/TLS. Data stored on your device is held in the App's private storage area, which the Android operating system isolates from other applications. We apply reasonable technical and organisational measures appropriate to the limited data we handle. No method of transmission or storage is completely secure, however, and we cannot guarantee absolute security.

11. Advertising content

Advertisements displayed in Knowcall are supplied by the third-party networks listed in Section 3 and are not created, selected or endorsed by us. Tapping an advertisement may open a third-party website or store listing that is governed by that third party's own terms and privacy policy. We are not responsible for third-party content, websites or practices; please review their policies before providing them with any information.

12. Changes to this Policy

We may update this Policy from time to time. When we do, we will change the "Last updated" date at the top and post the revised Policy at this URL. For material changes we will provide additional notice within the App where practicable. Your continued use of the App after a change takes effect constitutes acceptance of the revised Policy.

13. Contact us

Tranquil Mind Technology JSC
No. 3, Alley 98, Vu Trong Phung Street, Thanh Xuan Ward, Hanoi City, Vietnam
Email: contact@tranquilmind.co

© 2026 Tranquil Mind Technology JSC (@Tranquil Mind Technology JSC). All rights reserved.