Privacy policy — JustShutApp
Last updated: 2 October 2026
JustShutApp filters incoming calls on your phone. This describes exactly what it does with your data. It is written to be checkable against the source code, which is where the real answer lives.
What stays on your device
All of it, unless you explicitly opt in to sharing number ranges — the one exception, described in full below.
- Your call history in the app. Every screening decision — the number, what we did, which rule did it — is stored in a local database and never uploaded. It is capped at the 2,000 most recent calls.
- Your blocked and allowed lists, and any number ranges you added.
- Your contacts. If you grant contacts access, the app reads phone numbers only — never names, email addresses, photos or any other field — to make sure people you know are never filtered. Those numbers are kept in the app's own private storage on this device so that a call arriving moments after your phone restarts can still be matched against them; reading them afresh takes longer than the few seconds Android allows for screening a call, and a contact who could not be matched in time would be treated as a stranger. They are never transmitted, never shared, and are removed when you uninstall the app. Refusing the permission does not stop the app working — every caller is simply treated as unknown.
- Your settings.
The app is excluded from Android cloud backup, so none of the above is ever uploaded to Google's servers. It is included in device-to-device transfer, so your lists and settings come across when you set up a new phone — that transfer runs directly between your two devices and nothing is stored anywhere in between. On Android 11 and below, where the two cannot be told apart, everything is excluded from both; use the app's own export/import instead. Uninstalling deletes all of it.
What is sent
Nothing at all, unless you agree to share number ranges. There is no account, no sign-in and no telemetry. Marking a call as spam records that on your phone, where it feeds your own blocked list and the range detection described below. That is never transmitted.
Sharing number ranges — opt in, off until you say yes
The app works out which ranges of numbers are calling you with marketing — the first six to nine digits, shared by thousands of subscribers. When it finds a new one, it asks whether you want to contribute it so that other people's phones can block the same callers. You can say no. If you say nothing, nothing is sent.
If you agree, this and only this leaves your phone:
| Sent | Never sent |
|---|---|
The range itself, e.g. 8035591 | Any phone number, whole or in part |
| How many numbers inside it your phone flagged, and how many it has seen | Which numbers those were |
| Whether the evidence was your own judgement or another app's spam label | Your contacts, call history, call times or durations |
| A random identifier created by the app for this installation | Your own number, your name, your device, your location, or any advertising identifier |
A range is not a phone number with the end removed. A six-digit range covers roughly ten thousand subscribers and cannot be reversed into the numbers that produced it. Ranges you typed in yourself are never shared — those are your own preference about your own phone, not something the app concluded.
The identifier is a random value generated on your phone the first time anything is shared. It is not derived from your device, your SIM, your Google account or your advertising ID, it is not used to track you, and it exists for one purpose: so that twelve phones reporting the same range can be told apart from one phone reporting it twelve times. It reaches the server only as a salted hash, and the salt is not stored alongside it.
You can stop at any time under Settings → Screening → Share ranges I detect. Turning it off stops all sharing and erases the identifier, so nothing further can be connected to what came before. Ranges already contributed stay in the aggregate — they contain nothing that identifies you, and there is no identifier left to find them by; if you want them removed anyway, write to the address at the end of this policy.
What is downloaded
Once a day the app fetches a community blocklist over HTTPS. This is an anonymous download of a static file, the same file for every user. Your device sends nothing in order to receive it beyond what any web request necessarily reveals — your IP address, and the fact that a request was made — which reaches only the file's host and is not recorded by us or linked to anything.
The file is cryptographically signed, and a list that fails signature verification is discarded rather than applied. You can switch this off entirely under Settings → Screening → Use the community list.
Permissions, and what each one is for
Only call screening is required. Every other permission below is optional, and refusing it disables one feature rather than the app.
- Caller ID & spam role — required. Lets Android hand JustShutApp the incoming number just before your phone rings, so it can be checked against your rules.
- Phone state — detects that a call started and ended, and whether you picked up. It reports only
ringing / in-call / idle. It does not identify the caller. - Call log (optional) — used for three things, all on your device only:
- Telling a call you rejected apart from one you missed. Android exposes that distinction nowhere else, and without it JustShutApp asks before blocking rather than blocking on its own. This reads one row, at the moment a call ends.
- Noticing that another caller-ID app on your phone flagged the number. Those apps' verdicts are not readable directly, but when one supplies a name for an unknown caller your dialer may save that name against the call — and for a flagged number the name is often the label itself. JustShutApp reads that same row and, if the name reads as a spam label, silences that number next time. It is read on your phone, is never uploaded, and never affects a number in your contacts.
- A one-off backfill when you first grant it. The app reads your recent call history (up to 5,000 entries) once, to learn which numbers have called you and which you never picked up. This is what lets it spot a block of consecutive numbers behind a campaign immediately, instead of after weeks of use.
The backfill stores, on your device: the phone numbers that called you, and a flag for whether each was blocked, declined, or never answered. It does not store call times, durations, directions, or anything about calls you made. Numbers in your contacts are skipped entirely. None of it is ever uploaded. The backfill is purely local; there is nowhere for it to go.
- Contacts (optional) — so people you know are never filtered. Phone numbers only, never names, kept in the app's private storage on this device and never transmitted.
- Display over other apps (optional) — draws the after-call sheet over your screen. Refused, the same options arrive as a notification.
- Notifications (optional) — the after-call prompt, and telling you when a number was blocked on your behalf.
JustShutApp does not request the SMS permission and cannot read your messages. Call audio is never recorded, accessed, or transmitted.
When the app blocks a number on its own
If you enable "Block number when you decline", rejecting a call from an unknown number blocks it immediately. You are always told, on screen or by notification, and undo is one tap. Contacts, allowlisted numbers, emergency numbers and the 1600 service series are never blocked this way.
JustShutApp also groups reported numbers into ranges: when enough numbers from the same block are reported and nothing you have vouched for falls inside it, the rest of that range is silenced. Every such range is listed in the app with its evidence and can be removed individually. This happens entirely on your device.
Analytics and advertising
There are none. No analytics SDK, no crash reporting service, no advertising identifier, no third-party trackers.
Third parties
The community blocklist is served as a static file from GitHub Pages, which sees the download request and nothing else.
If you opt in to sharing ranges, they are received by a small service we run on Cloudflare Workers, which acts as our processor and stores only what the table above lists. There are no other third parties, no SDKs, no analytics and no data processors. Your data is not sold, rented, or shared for advertising.
Your rights
Under India's Digital Personal Data Protection Act, 2023, you can ask what data relates to you and ask for it to be erased.
In practice we hold nothing that identifies you. The app has no account and no identifier tied to your person; everything it knows lives on your phone and is erased by uninstalling the app or clearing its storage. You can see all of it for yourself: Settings → Backup & data → Export writes the app's entire contents to a readable JSON file you choose the location of.
If you opted in to sharing ranges, what we hold is the list in "What is sent" above: number ranges, counts, and a salted hash of a random identifier. None of it names you or your phone, which means we have no way to look you up by it. Turning the setting off erases the identifier on your device and stops anything further being sent; write to us if you want contributed ranges withdrawn as well.
If a number of yours appears on the community blocklist and should not, write to the address below and it will be removed.
Children
JustShutApp is not directed at children under 18 and collects nothing that would identify one.
Changes
Material changes will be announced in the app's release notes before they take effect.