Privacy Policy

Last updated: 15th January, 2021

This privacy policy describes the information that's collected when you use the website, how it's stored and how it's used. Your privacy is very important, so the site only uses the bare minimum of information for correct operation.

Personal information

Information about your computer, including your IP address, operating system and browser type, is stored temporarily in log files and may be used for system administration purposes, such as diagnosing faults, analysing site statistics and maintaining security. This is common practice for almost every website in the world. The log files are kept for 3 days, after which they're deleted and the information is no longer accessible.

If you create an account, the site will collect and store:

  • A username chosen by you - this may be displayed to other users either now or in the future (for example, on leaderboards)
  • The e-mail address you provide - this won't ever be displayed to other users and is only used for account administration purposes, such as sending password reset e-mails

This information is stored in a password-protected database, using standard industry practices.

If the website sends you an e-mail - for example, the confirmation e-mail when opening your account - your e-mail address is stored temporarily in a log file for the purpose of diagnosing faults and maintaining security. The log files are kept for up to 2 weeks, after which they're deleted and the information is no longer available.

If you start an e-mail conversation by contacting one of the website's e-mail addresses, the e-mail conversation, including your e-mail address, will be archived in a mailbox and may be used to follow-up on your query (for example, to notify you that a feature you requested has been added), analyse trends (for example, to prioritise a feature that's been requested by multiple people) and maintain security.

You can ask for your conversation(s) to be deleted from the mailbox at any time by contacting the e-mail address below.

Your personal information will not be shared with any third parties.

Other information

If you create an account, the site will additionally collect and store:

  • The puzzles you've solved
  • Statistics such as your solving times and the number of hints used

This information may be displayed on the website alongside your username, for example on leaderboards or summarised puzzle statistics. It may also be combined, anonymously, with statistics from other users to provide rolled-up totals or averages.

Cookies and Browser Local Storage

This website uses cookies, as almost every other website does, to give you the best possible experience. Cookies are small text files that are stored on your computer or mobile device when you browse websites. The cookies on this website help to:

  • Provide statistics for puzzles - number of attempts, average solving time, etc.
  • Personalise ad content

This website does not use cookies to:

  • Collect any personally-identifiable information
  • Collect any sensitive information
  • Pass personally-identifiable or sensitive information to any third parties

If your browser is configured to use cookies and you continue to use this website, it will be regarded as acceptance of this cookie policy. If you wish to remove or not use cookies from this site, instructions are included below, although if you do, the site may not work as you expect.

The cookies used by this site are explained below.

Session Cookie

This website uses a cookie that stores, on your computer, information about the puzzle you're currently solving. This cookie is used to gather statistics about the number of times each puzzle has been attempted and solved, as well as the average solving time.

If you create an account, this cookie also stores the page (within this website) that you will return to after you've signed in.

Browser Local Storage

In addition to the cookies above, this website stores the puzzle you're currently solving in your browser's local storage, if it's available, including any numbers you've entered, cage combinations you've faded out, etc. This enables you to continue from where you left off if you close your browser or switch off your computer and return to it later.


This website uses Ezoic to provide ads. The Ezoic privacy policy can be found here.


This website uses Cloudflare to enhance speed and security, meaning that all traffic passes through Cloudflare's servers before arriving at this website. To understand and control what information Cloudflare collects and stores, see their privacy policy here.

Disabling Cookies

You can usually disable cookies by changing your browser's settings. However, doing so is likely to limit the functionality of this site and many others, as cookies are a standard part of many websites' operation. If you do want to disable cookies, you can learn how here.

Access to your information

You can ask for a copy of your personal information by sending an e-mail to

You can delete your account at any time by signing in, visiting the Account page and clicking Delete my account. This will immediately remove your personal information from the database, along with your saved puzzles, solving times, etc.

Compliance with the GDPR

The GDPR (General Data Protection Regulation) is important European Union legislation designed to protect the privacy of individuals and their data. The website operates in accordance with the principles of the GDPR. The data controller is:

  • James Gibbs
Daily Killer Sudoku