Privacy policy

Last updated 8 November 2026

Who we are

Lumby AI is made by Lumbus Technologies Limited (“Lumbus”, “we”, “us”), a company registered in England and Wales, number 16793515, with its registered office at 128 City Road, London EC1V 2NX, United Kingdom.

We are the controller of the personal data this policy describes. It covers the Lumby AI app for iPhone and Android, the server the app talks to, and this website. Questions about it go to lumby@getlumbus.com.

What stays on your phone

Every app you make, its records, its earlier versions, its reminders and your settings are kept on your phone, in Lumby’s own storage. They are not sent to us or to anyone else, unless you share an app with other people (see Sharing). Reminders are set by your phone itself.

Photos you add to an app are kept the same way: made smaller, in Lumby’s own storage, not in your photo library, and never sent to us, to the AI or to anyone else. Lumby uses your camera only when you take a photo, and opens your photos only to add the one you choose. A photo goes when you remove it or delete its record or its app; Lumby clears it away the next time it opens.

Your phone’s own backup, such as iCloud or Google’s backup, may include them, depending on how your phone is set up. That backup is between you and Apple or Google.

Export everything, in Settings, makes a file of your apps and records, which you share wherever you choose; photos stay on your phone and are not in the file. Delete everything, in Settings, removes it all from your phone, photos included.

When you ask the AI

Lumby’s AI can write a new app or change one. Lumby asks you first, and you can turn the AI off at any time in Settings. Without it, Lumby makes apps from its own starting points, and nothing is sent.

When you ask, Lumby sends these to our server, which passes them to the AI:

the words you typed;
today’s date, your phone’s time zone and your currency;
when you change an app, the app’s design (its screens, parts, field names and reminders) and how many records each field holds.

It never sends your records, your photos, your name or your account details to the AI.

The AI runs on a model provided by an AI company in the United States, which uses these to answer the request. Under its terms for business customers, it does not use them to train its models, and it deletes them within 30 days, unless they are flagged as breaking its usage policy or the law requires it to keep them longer.

What the AI writes is checked on our server and again on your phone before you see it.

Your account

Lumby makes an account only when it first needs one: the first time you ask the AI, send a report from inside the app, or buy a plan. Opening Lumby, or using it without these, makes nothing.

A guest. A new account is a random number, with no name and no email address.
If you sign in to keep your account, we also keep how you signed in. With Sign in with Apple, your email address, or the private address Apple gives us if you chose to hide yours; we don’t ask Apple for your name. With Google, on Android, your email address; Google also sends your name and profile picture, which are kept with your account but not used. With a code by email, your email address.
What we keep with your account: your username, if you chose one, and for 30 days one you changed from; who invited you, and the extra asks invites gave you; the people you blocked; your plan, and any plan you bought and when it ends; for each ask to the AI, when it was, what came of it, how much it used and the kind of any problem, never your words, so that we can count your asks each month and know what the AI costs; the reports you send; and, if you signed in with Apple, a token from Apple that we keep only so that we can revoke it when you delete your account.

Accounts are kept by Supabase, which runs Lumby’s database and sign-in.

Sharing is something you choose. Nothing is shared unless you share an app, join one, or send a link.

Your username. To share apps, you choose a username. It is what the people you share with see, and how they invite you. Anyone using Lumby can find out whether a username is taken. When you change it, we keep your old one for 30 days so that nobody else can take it and seem to be you; it goes when your account does.
An app you share, or join. Its design and its records are kept on our server, so that everyone in it can see and change them on their own phone, with who added or changed each record and when, and who is in it. Photos are never sent: they stay on the phone that took them. Everyone in the app sees everything in it, and its maker can see who is in it and take people out.
A join link shows the app’s name and design, its maker’s username and how many people are in it, to anyone who has the link, never its records. Its maker can turn the link off or change it.
A copy you send by link is the app’s design only, never a record. We count how often a copy is opened and added, tied to no one.
An invite link to Lumby: when someone new signs in through it, we keep who invited them, and each of you gets extra asks of the AI.
Blocking and reporting. You can block someone, and report a person or a shared app. We keep whom you blocked. A report about a person or a shared app gives us what you write, their username, which shared app it is about and the app’s design.

Reports

If you use Report this app, we receive what you write, the app’s name and design, and, when the AI made or changed the app, what you asked for. Never your records or photos. We read reports to fix problems and to act on anything harmful. A report stays with your account until you delete your account. When a report arrives, we get a short email saying one is waiting, without what it says.

Plans and payments

Lumby Plus is sold through Apple’s App Store and Google Play. Apple or Google takes the payment: we never see your card or bank details. RevenueCat keeps a record of what your account bought, taken from Apple’s or Google’s records, so that your plan works on your account. We keep which plan your account has and when it ends.

Email

We send email only about your account, never marketing: sign-in codes; a note that your account is deleted, when you delete it; notes when Lumby Plus starts, when you turn off renewing it and when it ends; and thanks when you send a report. Apart from a code, which goes to the address you ask for it at, they go only to an address you confirmed with a code, or the one Sign in with Apple or Google gave us, including the private address Apple gives us if you chose to hide yours, which Apple passes on to your own inbox. Resend sends them for us, and sees the address each goes to and what it says. Their pictures come from this website, the same for everyone, and nothing in our emails tells us whether you opened one. If you write to us, or reply to one of our emails, we keep your message and your address so that we can answer you.

Our server and this website

Vercel hosts Lumby’s server and this website. Like any web host, it handles the technical details every request carries, such as your IP address, to deliver it and to keep it secure. Our server’s log keeps one line for each ask to the AI: a job number, what came of it, what it used, and any problem found in what the AI wrote, which can include a few of the AI’s words. It never holds your records or your name.

This website uses no cookies, no analytics and nothing loaded from anyone else.

Who else handles your data

These services handle data on our behalf, to run Lumby:

An AI company in the United States, whose model Lumby’s AI runs on: what you type, as described above.
Supabase: accounts, sign-in, plans, asks counted and reports.
Vercel: hosting for Lumby’s server and this website.
RevenueCat: records of what an account bought.
Resend: the emails we send.

When you sign in with Apple or Google, or buy through their stores, Apple and Google handle your data under their own privacy policies (Apple, Google).

We don’t sell your data, and we don’t share it for advertising.

Some of these services handle data outside the UK, including in the United States. Where they do, we rely on the protections UK data protection law provides for it, such as the UK’s adequacy regulations or the International Data Transfer Agreement or Addendum.

Why we use your data

UK data protection law asks us to say why we may use your data:

to give you what you ask for, such as an account, a plan and the apps the AI writes: to carry out our agreement with you;
to send what you type to the AI: your consent, which you give in the app and can take back at any time by turning the AI off in Settings;
to count asks, stop misuse, keep Lumby secure and read reports: our legitimate interest in running a safe and fair service;
to keep records the law requires: a legal obligation.

How long we keep it

Your account and what is kept with it: until you delete your account. A guest account that nobody uses for 90 days is deleted automatically, unless it bought a plan that is still active or ended in the last 90 days.
Asks to the AI: when you delete your account, they are kept only as counts and costs, tied to no one.
Reports: until you delete your account.
A shared app: until its maker stops sharing it or deletes their account; then it is deleted from our server, and everyone keeps their own copy on their phone. If you leave an app or are taken out of it, what you added stays in it for the others, until it is no longer shared.
A copy sent by link: until the person who sent it deletes their account.
Sign-in codes: they stop working after 10 minutes.
Purchase records: RevenueCat’s are deleted when you delete your account. Apple and Google keep their own records of your purchases.
What the AI company keeps: as described under “When you ask the AI”.
Server logs: kept by Vercel for a short time, then deleted.

Your rights

Under UK data protection law you can ask us for a copy of your data, to correct it, to delete it, to limit or object to how we use it, and to have it in a form you can take elsewhere. Where we rely on your consent, you can take it back at any time.

Delete your account: in Lumby, open Settings, then Account, then Delete account. It deletes your account and what we keep with it straight away. There is more on deleting your account.
What is on your phone: Export everything and Delete everything, in Settings.
Anything else: write to lumby@getlumbus.com. We answer within one month.

If you are unhappy with how we handle your data, you can complain to the Information Commissioner’s Office (ico.org.uk). We would be grateful to hear from you first, so that we can put it right.

Children

Lumby can be used without an account, and nothing anyone makes in it leaves their phone unless they ask the AI, send a report or buy a plan. Asking the AI and buying a plan are not meant for children under 13. If you think a child under 13 has done either without a parent’s or guardian’s permission, write to us and we will delete the account.

Keeping it safe

Everything Lumby sends travels encrypted. On your phone, your sign-in is kept in the iPhone’s Keychain or Android’s Keystore. Our database lets phones read none of its tables, and the keys that reach it are kept only on our server.

Changes to this policy

When this policy changes, we will update this page and the date at the top.

Contact us

Email lumby@getlumbus.com, or write to Lumbus Technologies Limited, 128 City Road, London EC1V 2NX, United Kingdom.