Privacy

Short version: your figures never leave your device.

No accounts, no cookies

You don't sign up or log in. Hundred Line doesn't set cookies and doesn't use analytics, adverts or tracking of any kind.

Everything happens in your browser

• All the sums are worked out by code running in your browser.
• The figures you type in are saved in this browser's local storage on this device, so they're there next time you visit. Nobody else can see them, including us.
• Nothing you type is sent to a server. The site loads no third-party scripts or fonts, and its security settings block the page from sending data anywhere.

Backups

Back up downloads your figures as a file to your device. Restore reads a backup file in your browser. The file isn't uploaded anywhere. Keep it somewhere safe, because it contains your salary and family details.

Deleting your figures

Use "Delete my saved figures" in Your details, or clear this site's data in your browser settings. Either removes them completely; we hold no copy.

Hosting

The site is hosted on Cloudflare. Like any website host, Cloudflare handles the basic information your browser sends when it asks for a page, such as your IP address, to deliver the site and protect it from attacks. That never includes the figures you enter.

Information, not financial advice

Hundred Line is a planning calculator. It isn't financial advice and can't know your full circumstances. Check big decisions with a regulated financial adviser or tax adviser.

Contact

Hundred Line is made by Side Door Studio. For questions about privacy, or to report a problem, email [email protected]. If you email us, we only use your message and address to reply.

Last updated 31 October 2026.