Nhat Nguyet: Lunar Calendar
Family reminders, lunar dates
Free · In-App Purchases
Ask Nhật Nguyệt AI and see its sources. One person adds a memorial day or festival, the whole family is reminded. A sourced library, regional customs, look-up tools.
Nhật Nguyệt is where a Vietnamese family keeps its memorial days and festivals together, and a sourced library of Vietnamese culture. In one app: an AI assistant that cites sources; shared family reminders; a library of traditional East Asian learning (huyền học); regional customs guides; look-up tools.
Nhật Nguyệt AI
- It answers from Nhật Nguyệt's published articles and numbers its sources; tap a number to open it.
- Asked about family dates, it reads your reminders and groups, only when asked, and changes nothing.
- Asked what will happen, it says it cannot tell; it shows what the texts say.
- Sign-in required. The app asks consent first: questions go to a third-party language model. Answers can be wrong; each has a report button.
Family memorial days and festivals
- One person adds a death anniversary (giỗ), birthday or full moon day; the whole group is reminded.
- A giỗ follows the lunar calendar: add it once and the app reminds you each year.
- Create a group and send an invite link (sign-in needed; 2 groups per account, 3 people each). Your own reminders need no account.
- Group content can be reported, members blocked.
A library of traditional learning
- Over 1,400 articles and a dictionary on the calendar, festivals, customs, Tử Vi, Bát Tự, the I Ching, house feng shui and numerology, as cultural knowledge: origin, books, where schools differ.
- Each field states its evidence level: the calendar is computed and cross-checked; customs are documented; Tử Vi, Bát Tự and the I Ching are one school's rules, not verified.
Customs and ritual steps by region
- Guides for memorial days, full and new moon days, the Kitchen Gods day, Tết, weddings: what to prepare day by day, each item with a sourced article.
- Regional differences are noted. Festivals by month, with venues.
Tools built on the library
- Today's page: Gregorian and lunar date, stem and branch, solar term, the almanac's auspicious hours (giờ hoàng đạo). Two-way date converter.
- Dates use Vietnam time (UTC+7) and Hồ Ngọc Đức's algorithm, checked against 2,474 NASA new moons and 4,824 Paris Observatory solar terms. Open data (CC BY 4.0): nhatnguyet.org/du-lieu
- Days by occasion in the almanac, the Lỗ Ban ruler, baby names, Tử Vi and Bát Tự charts, an I Ching reference, numerology.
- Each result states its kind of knowledge, its book or school, and each step: for reference, not professional advice.
- Home Screen and Lock Screen widgets. Apple Watch: lunar date, the almanac's hours, upcoming reminders.
Đoàn Viên plan (optional): an auto-renewing monthly or yearly subscription for larger families (more and bigger groups, up to 50 family profiles, 50 assistant questions a day). The calendar, reminders, look-ups and articles work without it. The yearly plan starts with a 7-day trial; price and renewal terms are shown before you confirm.
Personal readings (optional in-app purchase, per reading). Nhật Nguyệt is built knowledge-first: sourced articles, a calendar engine and open data came first; readings grow out of them. A reading is a structured report, not generic remarks: our engine computes your Bát Tự or Tử Vi chart or numerology numbers from your birth data, then formulas and experience a tradition wrote down are applied to those facts, each point cited to books such as Tử Vi Đẩu Số Toàn Thư (attributed to Chen Tuan) and Tam Mệnh Thông Hội (Wan Minying, Ming). A language model writes the text; it can be wrong. It reports what the books say, not verified: no guarantee, no substitute for medical, legal or financial advice.
Privacy, no ads
- No ads; the app does not track you across other apps or websites.
- The birth date you enter is saved on your phone and sent to our server to compute results; if you sign in, it is also saved to your account.
- Delete your account in the app (Me, Your data, Delete account).
Feedback: lienhe@nhatnguyet.org
Terms of use: https://nhatnguyet.org/dieu-khoan-su-dung
Privacy policy: https://nhatnguyet.org/chinh-sach-du-lieu
Ratings & Reviews
- This app has not received enough ratings or reviews to display an overview.
Version 1.0.3:
- Reminders can alert you several times ahead: pick up to three of 1 day, 3 days, 1 week, 2 weeks, 1 month.
- Reminders are coloured and filtered by type; Merge duplicates is easier to find on the reminder screen.
- A group can have several admins; a member's change to a group reminder waits for an admin to accept it.
- Swipe sideways to change the day on the Today page; it also works offline.
- Apple Watch: a new upcoming reminders screen and three display styles.
- The assistant reads group reminders when you ask, answers with a table and links straight to the right screen.
- Notifications can include a picture.
- New: personal readings, a written report based on your birth date and built on the Nhật Nguyệt library, each point quoting books with their sources (in-app purchase).
Feedback: lienhe@nhatnguyet.org
The developer, Giap Le Trong, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Linked to You
The following data may be collected and linked to your identity:
- Purchases
- Contact Info
- User Content
- Identifiers
- Other Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Provider
- Giap Le Trong
- Size
- 44.3 MB
- Category
- Reference
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Apple Watch
Requires watchOS 10.0 or later.
- iPhone
- Languages
English and 2 more
- English, Simplified Chinese, Vietnamese
- Age Rating
12+
- 12+
- Infrequent
Medical Treatment Information
Alcohol, Tobacco, Drug Use or References
Contains
User-Generated Content
Health or Wellness Topics
- In-App Purchases
Yes
- 99 personal readings 6.899.000đ
- 9 personal readings 899.000đ
- 1 personal reading 149.000đ
- 3 personal readings 349.000đ
- Đoàn Viên, yearly 199.000đ
- Đoàn Viên, monthly 29.000đ
- Copyright
- © 2026 Nhật Nguyệt