Privacy Policy
Last updated 19 September 2026
Kith4 is an app for sharing expenses with the people in your life. This policy explains what the app stores, why, and how to get it removed. It is written to be read, not to cover anyone in fog.
Who is responsible
Kith4 is made by Miguel Ruiz, an individual developer based in the Netherlands, who is the data controller for the purposes of the GDPR. Contact: privacy@kith4.app.
What Kith4 stores
| Data | Why |
|---|---|
| Your email address and password | To create your account and sign you in. The password is stored only as a cryptographic hash, which cannot be read back. |
| Your display name, and an avatar icon, colour or photo if you choose one | So the people you share expenses with can recognise you. |
| The contacts you create: the name you give them, and their email address if you invite them | To attribute expenses, and to deliver an invitation if you send one. |
| Your expenses: title, amount, currency, date, whether it is an expense or income, who paid, and how it splits | This is the content of the app. |
| A history of changes to each expense | So both people in a shared expense can see what changed and when. This history cannot be edited. |
The lawful basis for all of it is performance of the contract between you and Kith4: without this data the app cannot do what you installed it to do.
What Kith4 never does
- Your data is never sold, and never shared with anyone for their own purposes.
- No tracking across other companies’ apps or websites, and no data brokers.
- Kith4 does not connect to your bank, never sees your accounts, cards or transactions, and does not move money.
Understanding how the app is used
To decide what to improve and what to build next, Kith4 may measure how the app is used — for example which screens are opened and which features are used, and how often. This is about the app, not about your finances:
- it does not include the content of your expenses — no titles, amounts, notes, or the names of your contacts;
- it is used only to improve Kith4, never for advertising, and never sold;
- it is not combined with data from other apps or websites.
Kith4 does not measure usage yet. Before it starts, the provider will be listed on this page, and where the law requires your permission the app will ask for it — and you will be able to turn it off in Settings.
Advertising
Kith4 has no advertising today, and the hope is that it never will. But running it is not free — servers, email and the App Store all cost money — so at some point Kith4 will need to charge for the app or show adverts. Either way, you will be told in advance, in the app and on this page. If adverts ever come, they will not be based on your expenses or your contacts.
What other people can see
This is the point of the app, so it is worth being precise. When you share an expense with a contact who also uses Kith4, that person can see the expense, its amount, date and split, and your display name and avatar. They cannot see:
- any other contact of yours, or that any other contact exists;
- any expense they are not part of;
- the name you gave them in your own contact list.
Contacts who do not use the app see nothing at all. They exist only as an entry in your own list.
Who processes data on Kith4's behalf
Kith4 uses a small number of service providers, each bound to process data only on instruction:
| Provider | Role | Where |
|---|---|---|
| Supabase | Database and accounts | Ireland (EU) |
| PowerSync | Synchronising data to your phone | Ireland (EU) |
| Resend | Sending account emails, such as sign-up codes | Ireland (EU) |
| Cloudflare | This website, and forwarding email sent to kith4.app | Global network |
| Apple | App distribution, and crash reports only if you have opted into sharing them with developers in iOS settings | Global |
On your phone
Kith4 keeps a copy of your own data on your device so the app works without a connection. It is removed when you delete the app, and when you sign out.
How long data is kept
Your data is kept while your account exists. Deleting your account works as described below. Backups of the database are kept for a short period by the database provider and are overwritten in the normal course of operation.
Deleting your account
You can delete your account in the app, under Settings. When you do:
- your account is permanently closed, your password is invalidated and every session is signed out;
- your email address is released, so you can sign up again later with the same address;
- your name and avatar are removed, and your profile shows as "Deleted User";
- invitations you sent that were still pending are withdrawn;
- people you shared expenses with are shown that you have left.
Expenses you shared with someone else are not deleted. A shared expense is a single record that belongs to both of you: removing it would silently change the other person's balance and history. If you want a shared expense gone as well, delete it in the app before deleting your account, which removes it for both of you. For anything you cannot reach yourself, write to privacy@kith4.app.
Your rights
Under the GDPR you can ask for a copy of your data, correct it, have it erased, restrict or object to its processing, and receive it in a portable format. Most of this is available directly in the app; for the rest, write to privacy@kith4.app and you will get an answer within one month. If you are not satisfied, you can complain to your national data protection authority — in the Netherlands, the Autoriteit Persoonsgegevens.
Children
Kith4 is made for families, so children are part of it — but as people in the expenses, not as account holders. Accounts are for adults, aged 16 or over.
Parents often record expenses for their children: a name in a title such as “Mia · school trip”, or a note about a dentist visit. That information sits in the parent’s account, is visible only to the people that expense is shared with, and is removed when the expense is deleted. There is no need to put sensitive details, such as medical information, in titles or notes — a short description is enough.
Changes to this policy
If this policy changes in a way that matters, the date at the top changes and the app tells you before the change takes effect. Anything that needs your permission will ask for it rather than just announce it. Earlier versions of this page are available on request from privacy@kith4.app.