Privacy Policy

The short version

Tiang shows you no ads, and sells nothing about you. The Android app does carry one piece of advertising machinery: a Meta component inside it tells Meta each time the app is installed or opened, and how long you used it, and reads your device’s advertising ID so Meta can tell whether an ad for Tiang led to the install. You can delete or reset that ID yourself in Android’s own settings. The iPhone, iPad and Mac app has no Meta component and never asks to track you. Nothing is sold, and nothing goes to a data broker. The app also sends anonymous usage data about itself, described below, so we can tell what to improve, and while you are signed in our server keeps a record of which days you used the app, against your account. Your drawings live on your device; they are backed up to our server only while you are signed in with Tiang Pro and Sync is on, so you can reach them from another device, and Tiang Pro also keeps up to nine snapshots of them that you can restore. A free account does not sync at all. On any account, running a simulation sends that design to our server, which keeps the latest run. A floor plan you scan never leaves your device at all. You can delete your account, and everything synced to it, from inside the app.

What we collect

Your account

When you sign in with Google we receive your name, email address, profile picture and Google account ID. When you use Sign in with Apple we receive your Apple user ID, an email address, which may be an Apple private-relay address if you chose to hide yours, and your name, on the first sign-in only — no picture. We also keep the token Apple issues for that sign-in, so that deleting your account can ask Apple to revoke it. The account ID is how we know a returning device is you. A Google sign-in and an Apple sign-in are separate Tiang accounts, even when they show the same email address. If you set your own display name in the app, we show that instead of the one your sign-in provider gave us; the provider’s copy is kept too, and is deleted with the account.

You do not need an account to draw. Signing in is what turns on backup, sharing and subscriptions.

Your projects

While you are signed in and subscribed to Tiang Pro, your saved designs are backed up to our servers, unless you turn Sync off in the Profile tab. Sync is on to begin with and is set separately on each device; with it off, that device stops sending and receiving projects. A backed-up project holds the name you gave it, the building geometry, the materials and build-ups you chose, the country you picked for it, the map location and its place label, and your recent undo history. A signed-in account without Pro does not sync at all: it sends none of its designs up and receives none back. Whatever the server already holds for it stays there untouched and locked until the account is subscribed again or deleted. A project you delete on a free account is deleted on that device; the server copy, if there is one, is removed the next time the account is subscribed, or when you delete the account.

Whether or not you subscribe, when you run a simulation the design it is run on is sent to our server for that run. We keep your latest simulation inputs and results so re-running is fast, and any runs you explicitly saved for the Compare tab.

Backup snapshots

Tiang Pro includes Backup & Restore. A snapshot is a copy of every project you own, as it was at one moment, kept on our server so you can put it back on a device later. Each project in a snapshot holds the same things as a backed-up project above, apart from the undo history. Projects other people shared with you are never in your snapshots, and neither are scanned floor plans (they never leave your device) or simulation results. An account keeps up to nine snapshots, made in two ways:

Every 12 hours, at 00:00 and 12:00 UTC, our server copies your backed-up projects into a new snapshot, even when nothing has changed, and keeps up to the five most recent: each new one replaces the oldest. Nothing is sent from your device to make one. None is made for an account that has no Tiang Pro at that moment, has no project backed up, or has filled all nine places with backups of its own.
Back Up Now uploads every project you own from the device you are using, as it is right then, even when Sync is off, under a name you type. You have four of these. After that, each new one goes into a free place if there is one, or else replaces the oldest 12-hour snapshot, which is deleted; up to nine can be yours. They stay until you delete them.

The app also shows your backed-up projects themselves as “Latest Backup (Sync)”, which is why it counts ten; that one is not a separate copy. Restoring a snapshot downloads it and replaces the projects on that device; if Sync is on, the app first tries to finish a sync. The restore then turns Sync off, so our copy of your projects stays as it was until you turn Sync back on. You can delete any snapshot except “Latest Backup (Sync)” in the app, and it is removed from our server straight away. Deleting your account deletes every snapshot. If your Tiang Pro subscription ends, your snapshots stay on our server, kept but locked, like your backed-up projects: no new ones are made, and the app cannot list, restore or delete them until you subscribe again. To remove them without subscribing, delete your account.

Where you put the building

You pin the building on a map so the simulations can use the weather for that place. The latitude and longitude you choose are sent to our server and to the weather services below. This is a place you point at, not your device’s GPS — the app never asks for location permission and never reads where your device is.

Floor plans you scan — these stay on your device

If you import a PDF or a photo of an existing floor plan, the file is opened by the system’s own picker — Android’s file picker, or on iPhone, iPad and Mac the Files or Photos picker — which hands the app that one file and nothing else. The image is traced entirely on your device and is never uploaded to us or to anyone else. If you keep the plan as a backdrop to draw over, the picture is stored locally on your device; it is not part of the backup, and uninstalling the app from a phone or tablet removes it.

Subscriptions

If you buy Tiang Pro, the purchase itself is handled by Google Play on Android, or by Apple’s App Store on iPhone, iPad and Mac. We never see or store card or payment details. We use RevenueCat to keep track of subscriptions. Whenever you are signed in, on any of these devices and whether or not you subscribe, your Tiang account ID and account email are sent to RevenueCat, so a purchase can be matched to your account and restored on a new device, and so we can give Pro to an account by hand. If you signed in with Apple and hid your email, that email is Apple’s relay address. Our own server stores only whether your subscription is active and when it runs out.

How much you have used

The free tier includes a monthly allowance of runs, so our server keeps a count per account per month. It is a number, not a history: we record that a run happened, not what it was of. The size of the allowance depends on the version of the app, so each request carries the app’s version number and each queued simulation keeps the version that asked for it — an older app keeps the allowance it was installed with.

The same allowance is also counted per installation, so that signing in with a second account does not simply reset it. To do that the app makes up a random code when it is installed (the installation code) and sends it with those requests. It is not your device’s identity: the app invents it, it is not taken from the hardware and it is not the advertising ID described below, and it cannot be matched to you anywhere else. Clearing the app’s data gives you a new one. Reinstalling usually does too, but not always: Android can restore an app’s data, this code included, from your phone’s backup, and restoring an iPhone or iPad from an iCloud or computer backup brings it back too.

While you are signed in, our server also keeps a record for each day you use the app: the time of the first and the last request, how many requests there were, the app version and the installation code, stored against your account, together with which installation codes your account has used. With each installation code it keeps when that installation was first and last seen and your device’s region setting — a two-letter country such as ID or US, taken from the device’s language and region settings, not from GPS and not from your IP address. We use this to understand how the app is used, to notice one device signing in to many accounts to reset the free allowance, and to decide which countries to advertise in. The daily records are kept until you delete your account and are deleted with it; the installation record, with its region, stays after that (see Keeping and deleting, below).

How the app is used

Separately from that daily record, the app sends anonymous usage data so we can work out what to improve. It carries no identifier: nothing in it is linked to you, to your account, or to anything else you send us, and one device cannot be told from another. It does not include your designs, anything you type, or your location. You can turn it off in Profile → App Settings → About Tiang.

Ads that brought you here

We advertise Tiang on Facebook and Instagram. To know whether that money is doing anything, the Android app includes Meta’s measurement component — the facebook-core library from the Facebook SDK for Android (version 18.0.3), registered under our Meta app ID 1013978131237918. For every install, not only the ones that came from an ad, it tells Meta when the app is installed and each time it is opened, and how long each session lasted and how long it was since the one before. It sends your device’s advertising ID so Meta can connect that to an ad you were shown, and a random ID of its own that it makes up the first time the app runs and keeps for that installation (a restore from your phone’s backup can bring it back, like the installation code). If the Facebook app is also installed, the component can send the ID the Facebook app keeps for the phone as well (Meta calls it the attribution ID); newer versions of Android usually hide the Facebook app from other apps, so this mostly happens on Android 10 and older. With those events go device and app details of the kind any such component reports: the Android version, the device model, the app’s package name and version, which app store installed it, the language and time zone the phone is set to, the name of the mobile network, the screen’s size and density, the number of processor cores, and the phone’s total and free storage. If you installed Tiang from one of Meta’s ads, it also passes on the Play Store’s note of the ad link that led to the install. Meta’s own use of what it receives is governed by Meta’s privacy policy.

This is the one genuinely advertising-related thing in the app, and it is why the old promise never to touch an advertising identifier is gone from this policy.

What it does not send: your designs, your simulations, anything you type, your account, your email address, or where you pinned the building. Meta’s component can also report purchases — that part cannot attach to the payment library Tiang uses, so no purchase or subscription information reaches Meta.

The advertising ID is yours to control, outside this app: Android Settings → Privacy → Ads lets you reset it or delete it, and switch off ad personalisation. Deleting it stops the advertising ID being sent. It does not stop the component: Meta still receives the install, open and session events, the IP address they come from, and the component’s own random ID (and the Facebook app’s ID, where that is sent at all), whatever the advertising-ID setting and on every Android version. There is no switch for this inside the app: the component starts with the app.

On iPhone, iPad and Mac none of this happens. That app does not include Meta’s component, and it never shows Apple’s “Allow to track” prompt, so iOS does not give it the advertising identifier at all.

Support messages

If you use “Contact Us”, your email app opens a message to tiangbuildingapp@gmail.com. We then have your email address and whatever you wrote. The message is pre-filled with your app version and language so we can reproduce the problem — delete those lines before sending if you would rather not. We keep support mail only as long as it takes to sort the problem out.

Reminders

If you allow notifications, the app schedules its reminders on your device itself, from what it already knows there, such as when you last opened it. No push service is involved, and nothing about the reminders is sent to us.

Technical logs

Our servers record ordinary things like IP address, request times and app version, for security and for working out why something broke. The server’s own log lines also name the account ID behind many requests, and the email address of anyone you invite to a project. We have not set a fixed period for keeping these logs, and they are not removed when you delete your account.

What we never collect

Your contacts, your photo library, your messages, or your device’s GPS position. The app requests no location permission, no camera permission, no storage permission and no photo-library permission — scanning uses the system’s own file or photo picker, which hands over only the file you choose and needs none.

What we do with it

Create and manage your account, and keep you signed in.
Run the simulations you ask for — temperature, humidity, electricity and solar, and WiFi — against the place and the building you chose.
Back up a Tiang Pro subscriber’s projects, keep the snapshots they can restore, and make their projects available on their other devices.
Keep the service running, secure and debuggable.
Apply the free tier’s monthly allowance, and honour a subscription if you have one.
Understand how the app is used, and decide which countries to advertise in.
Work out whether advertising Tiang is worth paying for.

Who else sees anything

Only the services it takes to run the app:

Google: Verifies your sign-in if you use Google. On Android, Google Play also sells Tiang Pro and takes the payment.
Apple: Verifies your sign-in if you use Sign in with Apple, and receives a token-revocation request when you delete your account from inside the app. On iPhone, iPad and Mac, the App Store also sells Tiang Pro and takes the payment.
Open-Meteo: Receives the coordinates you pinned — latitude and longitude only, with nothing identifying you attached — and returns the weather for that place. If you search for a place by name on the map, what you type goes straight from your device to Open-Meteo, so it also sees your IP address.
PVGIS: The same coordinates, on the same terms. Operated by the European Commission’s Joint Research Centre, and used only as a fallback when Open-Meteo cannot answer.
OpenStreetMap and Nominatim: Map tiles, and turning coordinates into a place name. These requests go straight from your device, so those services also see your IP address and the area you are looking at.
RevenueCat: Your Tiang account ID and email whenever you are signed in, on any device, whether or not you subscribe, so a purchase can be matched to your account and follow you to a new device, and so we can give Pro to an account by hand. If you signed in with Apple and hid your email, this is Apple’s relay address. The RevenueCat component also starts with the app when you are not signed in, and then knows the device only by a random ID of its own — plus, on iPhone, iPad and Mac, the ID iOS gives every app from the same developer on that device (Apple calls it the identifier for vendor; it is not the advertising identifier).
Meta: From the Android app only: told each time the app is installed or opened, and how long each session lasted, with your device’s advertising ID, the component’s own random ID, the Facebook app’s ID for the phone where the component can read it, and the device and app details listed above, so it can tell whether an ad for Tiang led to the install. Nothing about your designs, your account, your purchases or where you pinned the building goes with it.
People you invite: If you share a project, the people you invite can see it — its name, its design and its map location — and, while you are working on it together, the email address on your account. You choose who, and you can revoke it at any time.

Meta is the only advertiser we share anything with, and only the install, open and session events described above. We share nothing with data brokers, and we never sell or rent your data.

Keeping and deleting

We keep your account while it exists. You can delete it, and everything synced to it, from inside the app under Profile → Delete My Account. That removes your projects, your backup snapshots, your saved and cached simulations, your undo history, your account’s usage counts, the daily records of when you used the app, and any shares, immediately.

You can also ask us by email at api.tiang.app/delete-account. We finish those within 30 days, apart from the few records the law requires us to hold.

Either way, some things are not removed with the account:

The installation record: the installation code, when it was first and last seen, the app version, the region setting and that installation’s monthly counts. After the account is deleted it is no longer linked to your account. It stays so that deleting an account cannot hand the device a fresh free allowance. Clearing the app’s data gives the device a new installation code, and reinstalling usually does too (Android may restore the app’s data, code included, from a backup, and so may restoring an iPhone or iPad from one).
RevenueCat’s record of your Tiang account ID and email, and of any purchase, if you ever signed in. Deleting your Tiang account does not remove it.
The server logs described under Technical logs above.
What Meta has already received from the Android app. Deleting your Tiang account does not reach it.

Deleting your Tiang account does not cancel a Google Play or App Store subscription. Cancel it first, where you bought it: Google Play → Subscriptions on Android, or Settings → your name → Subscriptions on an iPhone or iPad. Otherwise you will keep being charged for an account that no longer exists.

Security

Everything between the app and our servers is encrypted in transit over HTTPS.

Children

Tiang is meant for people aged 13 and over. It is not directed at younger children and we do not knowingly collect their data.

Changes

We may update this policy. When something material changes, the effective date at the top changes with it.

Contact

Questions about this policy or about your data: tiangbuildingapp@gmail.com.