In short
- Your measurements, stairs and saved projects stay on your phone. There's no account, no sign in and no server of ours. We never receive what you calculate.
- The free version shows one small banner ad at the bottom of the Stairs, Projects and Settings screens. It comes from Google's ad SDK (Google AdMob), and Google collects some data, such as your IP address and advertising ID, to show and measure ads and to prevent fraud.
- Where the law asks for consent (for example in the EEA, the UK and Switzerland), you're asked before personalized ads are used, and you can change your choice later in Settings, Privacy choices.
- Pro is an optional one time purchase. Google Play handles the payment. Pro removes the banner.
- A PDF leaves the app only when you share it yourself, to the app or person you pick.
1. Who we are
Stair Calculator & Stringer (“the app”, “we”, “us”) is published by manextapps. This policy explains how the Android app handles information. If you have a question, see Contact.
2. About the app
Stair Calculator & Stringer works out a straight stair from the total rise, the riser height and the tread depth, typed in feet, inches and fractions or in metric. Pro adds the stringer layout with framing square marks and boards to buy, L and U stairs with a landing, baluster spacing, and saved projects that you can share as a PDF.
All the math runs on your phone, and the app works offline. It goes online only to load the banner ad and the consent form, to talk to Google Play about the purchase, and when you open a link such as this policy. Keep in mind it's a calculator. Its results are estimates for planning. It doesn't approve plans or replace your local building code or a qualified builder.
3. Data we collect
We, the developer, don't run a server for this app and don't collect, receive or store personal data about you. There's no account or sign in, no analytics or crash reporting tool of our own, and no Firebase.
The banner ad comes from Google, which collects some data directly through its software development kit (SDK). That's explained in section 5. The optional purchase is processed by Google Play, see section 8.
If you email us, we'll receive your email address and whatever you choose to write. We use it only to reply, and we keep it only as long as that takes.
4. Data stored on your phone
So it can work, the app saves the following on your phone. None of it is sent to us.
- The stair you are working on: the values you typed (total rise, riser, tread, details, width, landing, balusters), so they're still there next time.
- Your projects: project names, the values you entered, and the results and drawing numbers saved with them.
- Settings: units, precision, your limits (max riser, min tread, headroom), haptics, theme and whether Pro was bought.
Google's ad, consent and billing libraries also keep some information on your phone, such as your consent choices, so they work correctly.
5. Advertising and Google's ad SDK
Ads come from the Google Mobile Ads SDK (Google AdMob), and Google's User Messaging Platform (UMP) asks for ad consent where that's required.
There's only one ad: a small banner at the bottom of the Stairs, Projects and Settings screens, above the navigation bar, shown in the free version. It never covers your values or results, and you won't see ads on the keypad, the Pro tools or the purchase screen. There are no full screen ads and no video ads. Buying Pro removes the banner.
What Google's ad SDK collects
According to Google's data disclosure for the Google Mobile Ads SDK, the SDK automatically collects and shares the following data:
| Data | Description |
|---|---|
| IP address | Your device's IP address, which may be used to estimate the general location of the device. |
| Product interactions | Interactions such as app launches, taps and ad views. |
| Diagnostic information | Performance data about the app and the SDK, such as launch time, hang rate and energy use. |
| Device and account identifiers | The Android advertising ID, the app set ID and, where applicable, other identifiers related to accounts signed in on the device. |
Your measurements, stairs and projects are never passed to the ad SDK. Google states that the data above is used for advertising, analytics and fraud prevention, and that it's encrypted in transit. Google may also use information from apps that use its services as described in How Google uses information from sites or apps that use our services and in the Google Privacy Policy. Google's handling of this data is governed by Google's own policies, not by us.
Personalized and non personalized ads
Personalized ads are based on things like your interests and past activity. Non personalized ads use more limited context, such as the app itself and your general (not precise) location. Depending on your choices, your region and your device settings, Google may show you personalized, non personalized or limited ads. Learn more in How Google uses cookies and similar technologies in advertising.
6. Consent and your ad choices
Where it's required (for example in the European Economic Area, the United Kingdom and Switzerland, and, where enabled, some U.S. states), the app shows Google's consent message when it starts. You can accept, decline or manage your choices.
When privacy options apply in your region, you can review or change your choices at any time under Settings, About, Privacy choices. If your choices mean no ad can be requested, the app still works fully.
You can also manage ad personalization for your Google Account at My Ad Center.
7. Your advertising ID
Android gives each device a resettable advertising ID. On most phones you can reset or delete it in Settings, Privacy, Ads (menu names vary by device and Android version). Deleting it stops apps from using it for advertising, and resetting it swaps it for a new random ID. Some phones also offer Privacy Sandbox ad settings in the same place.
8. In app purchase
Pro (product pro_unlock) is a one time purchase that adds the stringer layout, L and U stairs, balusters, saved projects and PDF sharing, and removes the banner. It's made through Google Play Billing: Google handles the payment and your payment details, and we never see them. All we get back is a confirmation from Google Play that Pro belongs to your Google account, so the app can turn Pro on and restore it on another phone with the same account.
9. Android permissions
The app doesn't ask for location, camera, contacts, microphone, notifications or storage access. A PDF is handed to Android's share menu, which needs no storage permission. The installed app includes these permissions:
- Internet access and network state: to load the banner, the consent form and the purchase screen.
- Advertising ID (
com.google.android.gms.permission.AD_ID): lets the ad SDK read the advertising ID. - Android ad services (
ACCESS_ADSERVICES_AD_ID,ACCESS_ADSERVICES_ATTRIBUTION,ACCESS_ADSERVICES_TOPICS): let the ad SDK use Android's Privacy Sandbox ad features where the phone supports them. - Google Play billing (
com.android.vending.BILLING): lets the app offer the Pro purchase. - Wake lock and foreground service: added by Android libraries that the ad SDK uses for short background tasks. Our own code doesn't run a foreground service.
10. Children
Stair Calculator & Stringer is a tool for building work and isn't directed at children. We don't knowingly collect personal information from children, and the app itself doesn't collect personal information from anyone. The banner is served by Google, which collects the data described in section 5. If you're a parent or guardian and have a concern, please contact us.
11. Data retention and deletion
- Our servers: we have none, so we keep no copy of your data.
- On your phone: your stair values and projects stay until you delete a project in the app, clear the app's data in Android settings, or uninstall the app.
- Files you shared: PDFs stay wherever you sent them until you delete them there.
- Google: data collected by Google's ad SDK and by Google Play is kept according to Google's policies. See the Google Privacy Policy and How Google retains data.
12. PDFs and new phones
Share PDF: a stair's PDF (drawings, results, stringer layout and cut list) is made on your phone and handed to Android's share menu. You choose the app or person it goes to. We never receive it.
Android backup: if backup to your Google Account is turned on in your phone's settings, Android may include the app's data (your stair values, projects and settings) in that backup, and a phone to phone transfer may copy it to your new phone. That backup is run by Google under your Google Account, not by us.
13. Sharing and links
We don't sell or share your personal data, because we don't receive any. Apart from Google's libraries described above, information leaves the app only when you choose to:
- Open a link, such as this privacy policy. This policy is hosted on GitHub Pages, and GitHub may log visitors' IP addresses for security under the GitHub General Privacy Statement. This page uses no cookies, analytics or tracking scripts.
- Contact us: the app opens your email app with our address filled in. You decide what to send.
- Share a PDF, as described in section 12.
14. Security
Since we don't collect your data, there's no copy of it on our side to protect or lose. Data on your phone is protected by Android's app sandbox. Google states that the data its ad SDK collects is encrypted in transit. No way of storing or sending data is completely secure, so we can't promise absolute security.
15. Your rights
Depending on where you live, privacy laws such as the EU and UK General Data Protection Regulation (GDPR), Canada's PIPEDA, Israel's Protection of Privacy Law, 5741 (1981), and U.S. state privacy laws may give you rights over your personal data. These can include the right to access, correct or delete it, to object to or restrict some processing, to withdraw consent, and to complain to a data protection authority.
- We don't hold personal data about you, so in most cases there's nothing for us to access or delete. Your data is on your phone and you can delete it as described in section 11.
- For data collected by Google, use your ad choices in the app (section 6), your phone's ad settings (section 7), and Google's own tools described in the Google Privacy Policy.
- You can always contact us, and we'll help as far as we can.
16. Changes to this policy
We may update this policy, for example if the app or the services it uses change. We'll post the new version on this page and change the effective date at the top. If a change is significant, we'll also mention it in the app's release notes.