In short: your sort code and account number never leave your browser
Privacy Policy
This page explains what happens to the data you type into Sort Code Checker, and what limited technical data is collected about visits to this site. The short version: the sort code checker itself runs entirely client-side, so the numbers you type are never transmitted anywhere.
The sort code checker tool
The format check, modulus check and bank lookup on the homepage all run using JavaScript in your own browser. There is no server-side component involved in the calculation – the sort code and account number you type are never sent over the network, never logged, and never stored anywhere except your own browser's local storage, which is used only to remember the last values you entered so the fields are pre-filled if you revisit the page. You can clear this at any time using the "Reset" button on the tool, or by clearing your browser's site data for this domain.
This is a genuine technical property of the tool, not just a policy promise: the calculation logic (src/lib/sort-code.ts, see the how modulus checking works page for what it does) contains no network request code at all – no fetch, no form submission, nothing that could send your input off your device even by accident. Anyone technically minded can verify this for themselves by opening their browser's developer tools, watching the Network tab, and typing a sort code and account number into the checker: no request will appear.
What "local storage" actually means here
Local storage is a small amount of storage space your browser sets aside per website, similar to a cookie but not sent to a server automatically the way a cookie is. This site stores exactly two things in your browser's local storage: your light/dark theme preference, and the last sort code and account number you typed into the checker. Both live only on your own device, in your own browser, and are readable only by this site (a basic browser security rule called the same-origin policy, not something this site has to implement itself). Neither value is ever transmitted, and clearing your browser's site data for this domain removes both immediately.
Website analytics
Like most websites, basic, aggregated visit data (such as which pages are viewed and which country a visit came from) may be collected for the purpose of understanding how the site is used and keeping it running reliably. This data is aggregated and is not used to identify individual visitors, and it is entirely separate from anything you type into the sort code checker itself, which as explained above never leaves your browser at all. This kind of aggregate analytics cannot see, and is not connected in any way to, the sort code or account number fields on the homepage.
Cookies and local storage
This site does not use tracking or advertising cookies. It uses your browser's local storage for two purposes only: remembering your light/dark theme preference, and remembering the last sort code and account number you typed into the checker (so the fields are pre-filled next time). Both are stored only on your own device and are never transmitted to us. There is no cookie banner on this site because there are no non-essential cookies requiring consent under UK GDPR/PECR rules – local storage used purely for the site's own basic functionality (theme, pre-filled fields) does not require one.
Third parties
This site does not sell, share or transmit any data you type into the sort code checker to any third party, because that data is never sent off your device in the first place. If you use the feedback form on this site, the message you submit is sent to us so we can read it – that is the only form on this site that transmits any user-entered data. The feedback form does not ask for or require your name, email address or any other identifying information; feedback submitted through it is anonymous unless you choose to include contact details in the message text itself.
Data retention
Because the sort code checker never transmits your input, there is nothing for us to retain from it – the concept of a retention period simply doesn't apply to data that was never received. Feedback messages submitted through the feedback form are kept only as long as needed to read and act on them. Locally stored theme and last-entered-values data lives entirely on your device and is retained for as long as your browser keeps it, or until you clear it yourself.
Children's privacy
This site does not knowingly collect personal information from anyone, including children, since the core tool does not collect personal information from any user by design. The site is a general-purpose reference and utility tool, not directed specifically at children.
Changes to this policy
If this privacy policy changes in a way that affects what data is collected or how it is handled, this page will be updated to reflect that. Since the checker's core no-data-leaves-your-browser design is a structural property of how the tool is built rather than a setting that could be quietly switched off, any future change to that specific guarantee would be a significant, visible change to the tool itself, not just a policy wording update.
Contact
Questions about this privacy policy or how this site works can be sent to contact@sortcodechecker.xyz. If you'd like more detail on exactly how the modulus check or bank lookup work under the hood, see how modulus checking works and the UK bank sort codes list.