Privacy Policy

Last updated 15 October 2026

Who we are

Sudoku: No Ads (the “app”) and the website playsudoku.io (the “website”) are made by Lockform Ltd, trading as Dalby Dev. Lockform Ltd is a company registered in England and Wales, company number 16987663, with its registered office at 4 Rosebery Mount, Shipley, BD18 2LB, England. In this policy, “we”, “us” and “our” mean Lockform Ltd.

This policy covers the app on every platform it is offered on and the version of the game on the website. If you have any questions, email jordan@lockform.io.

The app

What we collect

Nothing. The app has no sign-in, no advertising, no analytics, no crash-reporting service and no other third-party code that collects data. On Android it doesn't even ask for permission to use the internet, so it has no way to send anything anywhere.

What the app keeps on your device

So that you can carry on where you left off, the app saves these on your device only:

• the game you're playing, including your notes;
• your settings, such as theme, colour, sound and hints;
• your statistics, such as games won, best times and streaks;
• which daily puzzles you've played and your lesson progress.

None of this is sent to us, and none of it identifies you. You can clear your statistics in Settings → Reset statistics, and removing the app deletes everything it saved.

Device backups

On Android, your phone may include the app's saved games and settings in its own backup to your Google account, so they come back if you change phones. That backup is run by Google, not by us, and we can't see it. You can turn it off in your phone's backup settings.

Permissions

On Android the app asks for one permission: vibration, for the optional feedback when you tap. You can switch vibration off in the app's settings.

The website

Playing in your browser

The game on playsudoku.io runs entirely in your browser. Your games, settings and statistics are saved in your browser's local storage on your device and are never sent to us. Clearing your browser's data for playsudoku.io deletes them.

We don't use advertising, analytics or tracking cookies, and the website doesn't load anything from other companies' servers.

Hosting

The website is hosted by Cloudflare. Like any website, when your browser asks for a page, Cloudflare's servers receive technical information such as your IP address, browser type and the page requested. Cloudflare uses this to deliver the website and protect it from attacks and abuse, and it may set a strictly necessary security cookie for that purpose. We can see anonymous, combined statistics (for example, how many visits the website had) but not who you are. We rely on our legitimate interest in running a secure website to do this.

If you email us

If you contact us, we'll use your email address and message only to reply to you and help with your question. We keep the conversation for up to two years and then delete it, unless we need it longer to deal with a legal claim. Our email is handled by our email service providers, who process it on our behalf. We rely on our legitimate interest in answering your message.

App stores

If you download the app from an app store such as Google Play, the store handles the download under its own privacy policy. The store may give us anonymous, combined statistics, such as how many people installed the app and, if you've allowed your device to share them, reports of crashes. These don't tell us who you are.

If we ever offer optional donations, payments will be handled by the app store or a payment provider, not by us. We'll update this policy before that happens.

Children

The app and website are suitable for all ages. Because we don't collect personal data from anyone, we don't collect it from children either.

Where data is processed

Cloudflare and our email providers may process the limited information described above in countries outside the UK. Where they do, they are bound by safeguards recognised under UK data protection law, such as the UK International Data Transfer Addendum.

Your rights

Under UK data protection law (and the GDPR, if you're in the European Economic Area) you have the right to ask us for a copy of any personal data we hold about you, and to ask us to correct it, delete it, restrict how we use it, or object to us using it. In practice the only personal data we're likely to hold is an email you've sent us. To make a request, email jordan@lockform.io.

If you're unhappy with how we've handled your data, you can complain to the Information Commissioner's Office at ico.org.uk, though we'd appreciate the chance to sort it out with you first.

Changes to this policy

If we change this policy, we'll post the new version here and update the date at the top. If a change affects how we handle personal data, we'll make it clear in the app or on the website before it takes effect.