⏰ This product is scheduled for October 21st, 2026 12:01 AM PDT.

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Nhat Nguyet

Lunar calendar and family customs, with cited sources

1 follower

Lunar calendar and family customs, with cited sources

1 follower

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Calendar apps

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Knowledge base software

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Community management

Many families still live by the lunar calendar: death anniversaries, Lunar New Year, full moons. • Remember together: add a date once, the whole family is reminded on phone, web, watch or Telegram. • Do it right: a shared plan, the right prayer and custom. • Trust it: cited sources, a calendar checked against NASA and the Paris Observatory, open data with a DOI. • Understand it: Tử Vi, I Ching, feng shui, astrology and Tarot explained as traditions, with what is not proven.

Free

Launch tags:Android•GitHub•Lifestyle

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Maker

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Hi Product Hunt, I'm Kevin, the maker of Nhật Nguyệt ("Sun and Moon"). 95% of adults in Vietnam keep an ancestral altar at home, and about 6.5 million Vietnamese live abroad. Their most important family dates follow the lunar calendar and move every year. Nhật Nguyệt is a lunar calendar and family date book for them, and we built the knowledge base first so the features sit on something you can check. 1. Knowledge. 1,700+ articles on the Vietnamese calendar, customs and traditional Eastern metaphysics, in Vietnamese, English and Chinese. 376 carry sentence-level footnotes to books, archives and institutions. Our source catalogue lists 858 works, 475 of them public-domain classical texts. 2. Formulas. A lunar calendar engine in Vietnam time (UTC+7), tested against 2,474 NASA new moons and 4,824 Paris Observatory solar-term instants. Vietnamese Tết and Chinese New Year fall on different days in some years, 1985 being the famous one. The engine knows which. 3. Answers. An AI assistant that answers only from our published articles and shows the source numbers. Search computes direct answers, such as today's lunar date. 4. Family. A death anniversary (giỗ) is added once and the whole family is reminded every year, with a plan for who prepares what. 5. Personal readings. Bát Tự and Tử Vi charts computed by the engine, then read with rules from named classical books, cited by title. Each reading says it reports one school's rules, not tested science. Why I built it: I grew up in Nghệ An, where my parents kept every giỗ and full-moon offering by the lunar calendar. Like many Vietnamese who work far from home, my generation is losing track of those dates and the customs behind them, and I wanted something that remembers for us and explains why. Every result says what kind of knowledge it is. Mistakes go on a public corrections page. The data is open: 33 datasets under CC BY 4.0 with a DOI. No ads. Two questions for you: - If your family keeps lunar or religious dates, how do you remember them today? - What would make you trust a culture and reference app? I'm here all day to answer.

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1d ago

Forum Threads

p/nh-t-nguy-t

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1h ago

Nhat Nguyet 1.0.9: planning a family ceremony, together, inside one reminder

Release date 21 Oct, 2026

In a Vietnamese family, a death anniversary or the Lunar New Year is never one person s job. Someone buys the offerings, someone cooks, someone drives the grandparents, and someone has to remember which prayer to read. Until now, that planning happened in a group chat, while the reminder lived in our app.

Version 1.0.9 brings the whole conversation into the reminder itself.

p/nh-t-nguy-t

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1h ago

One family calendar, every screen

Grandma s death anniversary falls on the 15th of the 9th lunar month, a different solar date every year. One aunt lives in Saigon, a cousin is in Melbourne, and the person who usually remembers is busy that week.

Nhat Nguyet was built so that nobody in the family misses it.

One reminder, the whole family

Add the date once, in lunar terms. Everyone in the family group gets it at the same time, wherever they are:

p/nh-t-nguy-t

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13h ago

One knowledge base, six entry points: following a single question through Nhat Nguyet

What do I need to prepare for a first death anniversary?

0.0s. Typed into search. The app first works out what kind of question it is: a how-to, not a date and not a calculation. It answers with a passage quoted word for word from our article on the first death anniversary. The footnote points to Phan K B nh s 1915 book on Vietnamese customs.

Tap Set a reminder . Death anniversaries follow the lunar calendar, so the engine converts the date to this year s and next year s solar dates. No guessing.

Two weeks before. The reminder unfolds into a checklist: incense, sticky rice, the five-fruit tray. The tray follows your home region. The North and the South arrange it differently, and the app says so instead of quietly picking one.

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