Privacy Policy

Updated: 2 October 2026 · Applies to the Lich Van Nang Android app (com.lichvannang.lichvannang)

Lich Van Nang (“the app”) is a Vietnamese lunar calendar with auspicious-day guidance, prayers and an ancestral anniversary book. The app has no accounts: there is no sign-up, and we never ask for your email or phone number. This page explains what stays on your device, what leaves it, and what you control.

The app handles deeply personal information: your date and time of birth and the names of deceased family members. The rule is enforced in the source code itself: this data never enters analytics, and only leaves your device if you switch on sync yourself.

Data that stays on your device

The following is held in the app’s private storage on your phone and is not uploaded to any server of ours:

Date of birth, time of birth and gender — used for zodiac-year conflicts, the Tu Vi chart and your zodiac sign
The display name and avatar you choose
The anniversary book: names, relationships, lunar dates, notes, grave notes
Events you create: title, time, place, reminders
A photo you pick as wallpaper (copied into the app’s own folder)
Theme, text size and saved prayers

We do not run any server that stores your personal data and hold no copy of it.

What the app sends over the internet

What	Why	Who receives it
Approximate location — coordinates are rounded to a grid of about 110 metres before being sent. The app only requests coarse location (`ACCESS_COARSE_LOCATION`), never precise location.	To find temples, pagodas and churches near you	Our content server, which in turn calls Google Places. Coordinates are not stored against any identity; the server only caches results per grid cell for 10 minutes.
Advertising ID, approximate location inferred from IP address, device information and your interactions with ads	To show banner ads — the revenue that keeps the app free	Google AdMob (Google LLC)
Usage events — for example: a screen was opened, an anniversary was saved, a prayer was read. Includes app version and device model.	To see which features are used and to find bugs	Google Firebase Analytics
Crash reports — technical stack traces when the app fails	To fix bugs	Google Firebase Crashlytics
The anniversary book — only if you turn sync on yourself	To keep your records when you change phones	Your own Google Drive, in the app’s private area (`appDataFolder`). It does not pass through any server of ours, and we cannot read that file.
Wallpaper catalogue and display configuration	To refresh wallpapers without shipping an app update	Our content server. No information about you is sent with it.

Ads and your choices

The free version shows a single banner ad directly above the navigation bar, on five main screens: Home, Month, Events, Culture and Tools. Ads are served by Google AdMob.

Five places never carry ads, even on the free version: the prayer reader, the bell screen, the wooden-fish screen, the prayer-bead counter, and the entire anniversary book. You are praying, meditating, or looking at the anniversary of someone who has died — no ad belongs there. This rule lives in the source code and is guarded by an automated test.

Google may use the Advertising ID to personalise and measure ads — see How Google uses information from sites or apps that use its services.
You can reset or delete your Advertising ID at any time under Android Settings → Privacy → Ads. Deleting it makes ads non-personalised — you still see ads, they are just less relevant.
Buying Premium removes all ads.

What is NEVER sent to analytics

This list is hard-blocked in the source code — sending any of it makes the app fail immediately rather than merely warn:

Date of birth, time of birth, legal name
Names and relationships in the anniversary book
The content of any note you write
Coordinates and addresses
Display name and avatar

Where a figure is needed, only a bucket is sent (for example “between 1 and 5 records”), never the real value.

Permissions, and what happens if you decline

Permission	When it is used	If you decline
Approximate location	Only when you open “Temples nearby”	The app works normally; that screen lets you search by name instead.
Notifications	Reminders for anniversaries, new moon and full moon days	Everything else still works, you simply get no reminders.
Exact alarms	Firing a reminder at the time you chose	The app falls back to inexact alarms, which may be a few minutes late.
Photos	Only when you pick a photo as wallpaper	No impact. The app uses the Android Photo Picker, so no gallery permission is needed.

The app does not read your contacts, system calendar or messages.

Children

The app is intended for people aged 18 and over and is not directed at children. We do not knowingly collect data from children.

Your rights

Under Vietnam’s Decree 13/2023/ND-CP on personal data protection you may access, correct, export and delete your data. The app does all of this on the device, with no request to approve:

Access — Settings → Privacy & data → “View stored data”
Correct — edit directly on the relevant screen
Export — Settings → Privacy & data → “Export data”, producing a JSON file you keep
Delete — Settings → Privacy & data → “Delete data on this device”. This also deletes the copy in Google Drive if you ever enabled sync. Deletion is permanent.
Withdraw sync — turning the sync switch off deletes the Drive file immediately

Uninstalling also removes all data from the device. If you uninstall without first turning sync off, remove the Drive copy manually under Google Drive → Settings → Manage apps.

Purchases

Premium is billed through Google Play. We never see or store your card details — Google handles all of it.

Reference content

Prayers, festivals, Tu Vi charts, numerology, Lo Ban rulers and auspicious-day scores are traditional reference material, not medical, legal or financial advice.

Changes to this policy

When the app changes how it handles data, this page is updated first and the date at the top changes with it.

Contact

Email: chuga1204.develop@gmail.com