Terms of Use

Effective date: 19 November 2026 · Version: 1.0.0

This is an English translation provided for convenience. The Vietnamese version is the official text; if the two differ, the Vietnamese version applies. Button and menu names are given in English; the website and the app show them in Vietnamese.

These terms are an agreement between you and the operator of Ngày Gia Tiên. They bind you from the moment you click “Agree”: the website and the app ask for this before saving data for the first time and when you sign in. Only viewing the lunar calendar, converting dates or calculating death anniversaries without saving anything does not require agreement. How we process data is described in the Privacy Policy.

1. Provider and service

Provider

The website ancestordays.com and the Ngày Gia Tiên Android app are operated by an individual: Nguyễn Minh An (“we”). Contact: [email protected].

Service

Ngày Gia Tiên helps you convert between lunar and solar dates, calculate death anniversaries and the milestones after a death (the eve of the anniversary, 49 days, 100 days, the first and the final anniversary of mourning), view the lunar calendar, and add those dates to your calendar. There is no advertising.

• No account needed: you can use every date calculation feature, keep a list in the browser, download .ics files and send a list by link. The data stays only on your device.
• With an account (sign in with Google): the list is synced between your devices.
• Calendar subscription (webcal): the calendar in your calendar app updates itself when you edit the list. It works with a Google account, or with an anonymous account the website creates for you when you are not signed in.
• Free plan and paid plans: date calculation, reminders, adding to calendars and looking up the lunar calendar are always free. Paid plans (Premium, Dòng họ and Dòng họ lớn, that is Clan and Large clan) let you keep more people in the account and use the features listed on the Plans page.

2. Accounts and acceptable use

Accounts

• You must be 16 or older to save data or create an account. People under 18 need the consent of a parent or guardian before buying a plan.
• You sign in with your own Google account. You are responsible for keeping your Google account and signed-in devices secure; every action from your account is treated as done by you.
• An account is for you and your family, not for providing a service to others.
• You can delete your account at any time under Account. Deleting the account deletes the synced list and the calendar subscription; download a backup first if you want to keep the list. Plans of a deleted account: see section 4.
• We may suspend or delete an account that breaches section 2 after telling you by the account’s email, with the reason. If the breach is harming the service or other users, we may suspend it first and tell you afterwards. You can respond or complain by email to the address in section 1. An account deleted for a serious breach (for example payment fraud, attacking the service) gets no refund for the rest of the plan; in other cases, we refund the unused time of a yearly plan.

Acceptable use

You must not:

• attack or overload the website or the app, or try to get around their protections, including data access rules and plan limits;
• access or try to access the data of another account;
• use automated tools to create accounts, write data or download content in bulk at a rate that affects other users;
• use an account or a calendar subscription to store or spread content that is not a list of death anniversaries, or content that is unlawful or offensive to others;
• resell a paid plan, share it with people outside your family, or commit payment or refund fraud;
• copy the website, the app or the source code to provide another service.

We may block access from sources that breach the above.

3. Plans and trial

• Limits and benefits: the maximum number of people, the benefits and the price of each plan are listed on the Plans page; that page is part of these terms. Without signing in, the list in the browser is not limited by plan (only by a technical limit so that the browser does not slow down).
• 30-day Premium trial: given automatically the first time you sign in with Google, once per Google account. No bank or credit card is needed, it does not charge you when it ends and does not turn into a paid plan by itself.
• The price of each plan is shown in Google Play before you buy. The price in Google Play is the price you pay.
• Plan changes: we may change the limits, benefits or price of a plan for later purchases and renewals, with notice under section 7. Changes that reduce benefits do not apply to a period you have already paid for. For Premium lifetime, we do not reduce the maximum number of people or the benefits listed on the Plans page when you bought it.

4. Buying, renewal, cancellation, refunds and when a plan ends

Buying, renewal, cancellation and refunds

• Where to buy: plans can be bought only in the Ngày Gia Tiên Android app, paid through Google Play. The website does not take payments; after buying, the plan works on the website right away with the same Google account.
• Yearly plans (Premium yearly, Dòng họ, Dòng họ lớn) renew automatically every year through Google Play until you cancel. Cancel in Google Play (Payments & subscriptions) or from “Manage plan” in the app; the plan keeps working until the end of the paid period.
• Premium lifetime is paid once, is tied to the Google account that bought it, and works for as long as the service operates. If the service ends, section 7 applies.
• When you delete your account: deletion automatically cancels the renewal of the account’s yearly plans, so you are not charged for the next period. A paid plan is kept for the Google account used: signing in again with that Google account lets a yearly plan continue until the end of the paid period and a lifetime plan continue as before, but the deleted list and settings cannot be restored. When the paid period ends, a yearly plan ends like any expired plan; to continue, turn renewal back on in Google Play before that date or buy again. Deleting the account does not give rise to a refund for the remaining time; the website and the app remind you of this before you confirm the deletion. If, because of a technical error, you are still charged after deleting your account, we refund that charge.
• Restore purchases: on a new Android device, tap “Restore purchases” to get back plans bought with the same Google Play account.
• Refunds: ordinary refund requests are handled under Google Play’s refund policy. In addition, if a plan does not work as promised because of our fault and we cannot fix it within a reasonable time, you get a corresponding refund through Google Play. When a payment is refunded, the corresponding plan is withdrawn.
• The operator is an individual and does not issue value-added tax (VAT) invoices. Payment receipts are sent by Google Play.
• Support by plan: by email to the address in section 1. Premium: reply within 10 working days. Dòng họ: reply within 3 working days and help preparing a list import file 2 times a year. Dòng họ lớn: priority, reply within 1 working day and help preparing the file 6 times a year. You can also import a list yourself from an Excel or CSV file in Settings. These are reply times, not resolution times.
• Unlimited plan: for lists of more than 1,000 people or clans that need dedicated support, under a separate written agreement (price, number of people, term, support channels such as phone and Zalo); not sold in the app.

When a trial or plan ends

If a trial or paid plan ends (not renewed, cancelled, refunded) and the list has more people than the limit of the plan you still have:

• You are told by a notice on the website and an email to the Google address of the account: when the plan expires and 7 days before the list is locked.
• You choose the people to keep with “Choose people to keep”; if you do not choose, the people at the top of the list are kept.
• Buying a plan again at any time, or deleting people until the list is within the limit, makes the list fully usable again.
• When a Dòng họ plan expires: groups stay as they are and can still be renamed; if there are more than 20 groups, no new group can be created until you buy again.
• Members of a family list do not pay; the rules above apply to the plan-based list of the person who created the list.

5. Data you enter and accuracy of dates

Data you enter and your responsibility

• The data you enter belongs to you.
• You should keep your own backups (the “Download backup” button), even when the list is synced to an account. For data in the browser: we cannot recover data lost because browser data was cleared, the device was changed or damaged, private browsing was used, or other software or people used your device. For data in an account: we keep it secure as described in the Privacy Policy; data lost because of our fault is covered by section 6.
• When entering information about a deceased person, you confirm that you are that person’s spouse, child, parent or another relative, or have the consent of those people, and enter only the information needed to remember the death anniversary.
• You are responsible for the information you enter, store and share. Anyone with a share link or calendar subscription address can see the names and dates in it; send it only to people you trust. If a calendar subscription address is exposed, click “Change link”.
• If a third party complains about information you entered or shared, you are responsible for resolving that complaint.

Accuracy of dates

• The lunar calendar is calculated with astronomical formulas for the Vietnam time zone and has been checked against published calendar tables.
• Death anniversaries are calculated according to common custom (for example, a death in a leap month is remembered in the regular month with the same number). Families and regions may do it differently; you can adjust the rules for each person.
• For important dates, check against a paper calendar or ask the elders in your family. We do our best to get results right but do not guarantee them absolutely.
• Reminders in calendar apps (Google Calendar, Apple Calendar…) are made by those apps. Some apps ignore reminders when importing .ics files, and each calendar app decides how often it reads a calendar subscription again.

6. Content, trademarks, third parties and limitation of liability

• The text, interface, source code and the name “Ngày Gia Tiên” belong to the operator. You are free to use the calculated dates for personal and family purposes.
• The service runs on third-party infrastructure and services (Google Firebase, Google Play, Amazon Web Services, Cloudflare), uses Google sign-in, and adds dates to third-party calendar apps. We are not responsible when those services fail, change or stop working, unless it is our fault. Payments, renewals and refunds through Google Play follow Google Play’s terms.
• We are not responsible for failing to meet our obligations because of force majeure, such as natural disasters, epidemics, widespread network or power failures, cyberattacks, or decisions of state authorities.
• We compensate actual, direct damage caused by our fault, under Vietnamese law. We are not responsible for indirect damage (such as lost opportunities or other costs incurred) or damage not caused by our fault. For paid plans, compensation does not exceed the amount you paid for that plan in the last 12 months, unless the law provides otherwise.
• The above does not exclude or limit any liability that Vietnamese law does not allow to be excluded or limited, and does not affect your rights under consumer protection law.

7. Changes and ending the service

• We may change the features of the service. If accounts and syncing have to end, we announce it on the website and by the account’s email at least 6 months in advance, unless a competent state authority requires an earlier end, so that you have time to download a backup. Yearly plans stop renewing from the announcement; a yearly plan with time left after the end date gets the unused time refunded through Google Play. Premium lifetime works until the end date. Lists in the browser and files you have downloaded are not affected.
• Changes to the terms are posted on this page with a new version and effective date. Important changes (affecting your rights, obligations or data) are announced on the website at least 15 days before they take effect, and you are asked to click “Agree” again before you continue saving data. Minor changes (wording, contact details) take effect when posted.
• If you do not agree with the new version, you can stop using the service, cancel your plan in Google Play, download a backup and delete your account. Changes that reduce benefits do not apply to a period you have already paid for (section 3).

8. Complaints, disputes and contact

Complaints and dispute resolution

These terms are governed by Vietnamese law. If there is a problem, you can send a complaint to the email in section 1; we reply within 15 working days. You have the right to choose how to resolve it: negotiation with us, mediation, a complaint to the state authority for consumer protection, or a lawsuit at a competent court in Vietnam.

Contact

Questions about these terms: [email protected].

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