Privacy statement
Effective date: 10 November 2026
KLO Calculator ("the app") and its web page ("the page") are made by KLO Technical Services Limited, trading as KLO Development Services, company number 16105032, registered office 23 Brook Road, Bomere Heath, Shrewsbury, Shropshire, SY4 3PU ("KLO", "we").
The short version
- Everything you type stays on your device. Sums, the tape, notes, construction calcs and your own supplier figures are kept on the device or in the browser you use. KLO never receives them.
- If you subscribe on the web, or sign in, we hold your email address and whether you're subscribed, in your KLO account. Nothing else: not what you type.
- No advertising, no analytics, no tracking. The app and the page collect no usage data, and don't track you across other apps or websites.
- Two things go over the internet: a request for the day's currency exchange rates, and, if you sign in, the KLO account check (in the app this includes your App Store subscription, so the same email unlocks the web page). Neither carries anything you've typed.
What is kept, and where
| What | Where it's kept |
|---|---|
| The calculator's sum, memory and last answer; the tape; Notepad sheets; what you've typed in each construction calc; your saved jobs; the currency rates last loaded; the conversions you last used | In the app: a file in the app's own folder on that device. On the web: in that browser's storage for calc.klodevelopmentservices.co.uk |
| Settings: significant figures, separators, sections and categories shown, your supplier figures, the screen you were on, and that you've read the notice about the construction checks | In the app's settings on that device. On the web: in that browser's storage |
Nothing is synced between devices, and nothing is backed up by KLO. The app's file is part of the device's own backup (iCloud or a Mac backup) if you have one turned on.
To remove it: delete the app, or on the web clear the site's data in your browser. In the app, Clear on the tape and Delete on a Notepad sheet remove those as you go.
The currency rates
When you open Convert › Currency, and at most every six hours after that, the app or the page asks api.frankfurter.dev for the European Central Bank's reference rates against the pound. The request says only "rates for GBP". Like any web request, it reaches that service from your IP address. Frankfurter is an independent service that republishes the ECB's rates; it isn't run by KLO.
Your KLO account and subscription
App Store. A subscription bought in the app is sold and managed by Apple. Apple tells the app whether it is active; we don't receive your payment details. Manage or cancel it in your Apple Account settings.
Your KLO account. To sign in on the web page, or to use the same subscription in the app and on the web, you use a KLO account: your email address, a sign-in token, and your subscription state (active, until when, bought on the web or through Apple). When you sign in in the app, it sends your App Store subscription to the account server so the web page unlocks too. The account is kept on our account server, run on Cloudflare (Cloudflare D1, Western Europe). Sign-in codes are emailed to you through Microsoft 365. We use this only to sign you in and decide whether editing is open. Lawful basis: contract. You can delete the account in the app (Settings › Subscription › Delete KLO account) or by emailing us. The KLO account is shared by the KLO apps that use one, so deleting it erases it for all of them, and cancels a subscription bought on the web.
Paying on the web. Web payments are taken by Stripe. Your email address, card details and billing address go to Stripe; we receive your Stripe customer reference and subscription dates. Stripe's privacy policy: https://stripe.com/privacy.
How long we keep it. Your KLO account (email address and subscription state) is kept while you have it and erased when you delete it. Sign-in codes stop working after a few minutes, and a sign-in token ends when you sign out or delete the account. Records of web payments (Stripe customer reference, subscription dates and invoices) are kept for six years after the end of the tax year they fall in, because UK tax law requires it (lawful basis: legal obligation). Support emails are kept for as long as we need them to help you, and no more than two years after the last message.
Who handles it, and where. Cloudflare runs the account server and the web page (data kept in Western Europe). Microsoft 365 sends the sign-in emails and holds support emails. Stripe takes web payments. Apple handles App Store purchases. Cloudflare keeps short-lived request logs, including your IP address, to run and protect the account server and the page. Each acts for us under its own data-processing terms. Some of these firms may move data outside the UK, including to the USA; where they do, they use the UK's approved safeguards (the UK International Data Transfer Addendum or the UK–US data bridge). When you email us for help, our lawful basis is legitimate interests: answering you.
Sharing and copying
When you share or copy the tape, a sheet or a calc's answers, they go where you send them, through your device's own share sheet or clipboard. KLO doesn't see them.
The web page
- Where it is: calc.klodevelopmentservices.co.uk, on its own address so that no other page can read what it keeps. The old address, apps.klodevelopmentservices.co.uk/calculator/, moves what that browser kept to the new address inside the browser itself, then clears it.
- Hosting: the page is hosted by Cloudflare. Like any web host, Cloudflare handles your IP address and browser details to deliver it, under its own privacy policy.
- Who it talks to: once loaded, only api.frankfurter.dev, for the currency rates, and the KLO account server (fees-cloud.klo-c79.workers.dev) if you sign in. Paying opens Stripe's own page.
Your rights
- Who is responsible. KLO Technical Services Limited is the controller of your personal data.
- KLO doesn't hold anything you type into KLO Calculator. The personal data we hold about you is your KLO account, if you have one, and any email you send us.
- What you can ask. You can ask us to see your data, correct it, delete it, limit or object to how we use it, or have a copy in a portable form. Email us; we answer within one month.
- Support emails. If you email us at [email protected], we use your email only to answer you. We keep it as set out in "How long we keep it". You can ask us to see or delete it.
- Buying it. See "Your KLO account and subscription" above.
- Testing it with TestFlight. If you test it through Apple's TestFlight, Apple shares with us the email address you were invited with, and any feedback, screenshots and crash reports you choose to send. We use them only to run the test and improve the app.
You can complain to the Information Commissioner's Office (ico.org.uk) if you think your information has been handled wrongly. We'd be grateful for the chance to put it right first.
Children
KLO Calculator is made for people in the building trade, not for children.
Changes
If this statement changes, the new version is put on this page with its date. If a change affects what leaves your device, it is described in the app's release notes too.
Contact
KLO Development Services, 23 Brook Road, Bomere Heath, Shrewsbury, Shropshire, SY4 3PU. Email: [email protected].