Privacy Policy

Last updated: 30 September 2026

Costline is a budget tracker from Apps By BAA. It is built so that your money data stays yours: it works without an account, it never connects to your bank or reads your email, and it has no analytics and no tracking. The free app on phones shows one non-personalized ad banner; Costline Premium removes it.

What stays on your device

Everything you enter — budgets, entries, amounts, categories, bills, notes and the names you give people in a budget — is kept in a database on your device (in the web version, in your browser's storage). Without an account, none of it leaves your device.

If you sign in (optional)

An account is only needed to use the same budgets on several devices or to share a budget.

• Your e-mail address is used to send you a one-time sign-in code. There is no password. The e-mails are sent through Resend.
• Your budgets are synced through our server on Supabase, hosted in the European Union (Frankfurt, Germany). The server keeps a copy of the budgets you sync so your other devices, and the people you share a budget with, receive them. Data travels encrypted (HTTPS), and the server lets an account read only the budgets it has access to.
• We use your e-mail address only to sign you in. No newsletters, no marketing.

Sharing a budget

When you invite someone to a budget, they see its entries, categories, bills and the names of its members, and you see what they add. Someone you remove, or who leaves, stops receiving the budget; the entries they added stay in it.

Bill import

When you import a bill from a PDF or a photo, it is read on your device (the PDF's own text, or text recognition on the device). The file is never uploaded and is not kept after you finish; only the entry you confirm is saved. To recognise bills from different countries and providers, the app downloads updated reading rules from costline.appsbybaa.com at most once a day. That request contains nothing about you or your bills.

Costline Premium

Premium (a shared budget, cloud sync, bill import and no ads) is a subscription bought through the App Store or Google Play. Apple or Google handle the payment; we never see your card or payment details.

• To know who has Premium, purchases are recorded with RevenueCat (RevenueCat, Inc.): an app user ID (the same ID your Costline account uses if you sign in), the products bought, the purchase and renewal dates, and the store's country and currency.
• If you sign in, our server stores whether your account has Premium and until when, so it also works on your other devices and on the web.
• Cancel or change your subscription at any time in your App Store or Google Play subscription settings.

Ads in the free app

The free app on iPhone and Android shows one small banner on the Home and Analytics screens. There are no ads with Premium, and none on the web.

• Ads are served by Google AdMob and are non-personalized: they are not chosen from your interests or your activity, and nothing you enter in Costline is shared with Google.
• To show and count ads and to prevent fraud, Google's SDK processes technical data such as your IP address (and the approximate location it implies), device and app identifiers, and which ads were shown or tapped. On iPhone, Costline never asks for permission to track you, so the advertising identifier is not used.
• In the European Economic Area, the United Kingdom and Switzerland, Google's consent message asks for your choice before any ad; you can change it at any time in More → Ad privacy choices.
• Google's privacy policy: https://policies.google.com/privacy — how Google uses data from apps that use its services: https://policies.google.com/technologies/partner-sites

Exchange rates

When you record an expense paid in another currency, Costline asks Frankfurter (api.frankfurter.dev), which publishes the European Central Bank's reference rates, for that day's rate. Only the two currency codes and the date are sent — nothing about you or your spending.

The web version

The web version at costline.appsbybaa.com is served by Cloudflare, which processes technical request data (such as IP addresses) to deliver the site. The app sets no cookies and has no analytics.

What we don't do

• No analytics SDKs, and no personalized advertising: the free app's ads are not chosen from your data.
• No tracking across apps or websites, and no selling of your data. Nothing you enter in Costline is shared with advertisers.
• No bank connections, no reading your e-mail, no cloud AI: bills are read on your device.

Your choices

• Export: More → Export your data gives you everything as CSV files, at any time.
• Delete entries or budgets whenever you like; deletions sync to your other devices.
• Delete your account in the app: Account & sync → Delete account. Your sign-in and everything synced to it are deleted from our server, including the budgets only you use. Budgets you share go on for the other members: the entries you added stay there and your name is removed. This device is cleared too.
• Sign out keeps your data on the device and stops syncing.
• Ads: Premium removes them; in the EEA, the UK and Switzerland, More → Ad privacy choices changes your consent.

Children

Costline is not directed at children under 13 and does not knowingly collect their data.

Changes

If this policy changes, this page is updated and the date at the top changes with it.