Period data is among the most personal information there is. So this site is built so that we never receive it at all.
What we collect
Nothing you enter. There are no accounts, no forms that send data and no analytics, and our code never sends your dates, symptoms or photos anywhere. Most pages do show ads from Google, which uses cookies. How ads work here.
Advertising and cookies
Most pages show ads from Google AdSense, which pays for the site. Google and its partners use cookies and similar technology to show and measure ads, which can be based on your visits to this and other websites. Like any service a page loads, Google receives standard details such as the page address, your IP address and your browser type. We don’t pass it anything you enter.
The tracker and the photo check have no ads. They’re where you log health data, so they load no ad code at all and keep the strict security rule described below.
In the UK, the European Economic Area and Switzerland, you’re asked for consent before personalised ads are shown, and you can change your choice at any time. Wherever you are, you can turn off personalised ads in Google’s Ads Settings, or opt out of some other companies’ advertising cookies at aboutads.info. You can also read how Google uses information from sites that use its services.
Where your data lives
The tracker saves your log in your browser’s local storage on this device. Calculator and checker answers aren’t saved at all, unless you choose to log them in the tracker. We can’t see, recover or share any of it.
If you switch between light and dark mode, that choice is also remembered in your browser’s local storage, and nothing else is stored with it.
This also means anyone with access to this browser could open your tracker, and we can’t restore your log if it’s lost. If you share a device, use a private browser profile and delete your data when you finish.
Photos
The photo check runs entirely in your browser. A photo is held in memory just long enough to read its colour, is never uploaded, and isn’t saved. Only the colour you confirm is kept, in your log.
How you can check this yourself
The tracker and the photo check are sent with a Content Security Policy that includes connect-src 'none', form-action 'none' and frame-src 'none'. These are instructions your browser enforces. They block the ways a page normally sends data in the background, and form submissions. To see it for yourself, open your browser’s developer tools on one of those pages, select the page in the Network tab and look for content-security-policy in its response headers. Pages with ads can’t carry this rule, because ads load from Google. There, the protection is that the site’s code never tries to send what you enter.
Your rights and controls
- See or move your data: save a backup file or a spreadsheet from the tracker.
- Delete your data: use “Delete everything” in the tracker, or clear this site’s data in your browser.
Because we hold none of your cycle data, there’s nothing for us to access, correct or delete on your behalf, and nothing we could hand over if asked.
When you choose to share
Nothing is shared unless you press a button. Each share option works directly from your device:
- Share, Copy text and Email pass your result or summary to your device’s share menu, clipboard or email app. You can preview the exact text first.
- Tracker summaries and spreadsheets always include your period dates and cycle lengths. Symptoms, colours, mood, mucus, temperature and notes are left out unless you tick them.
- Sending to another device shares a backup file containing everything you’ve logged, so only send it somewhere you trust.
- WhatsApp, Facebook and X links share only the public address of the page you’re on. They open those services in a new tab, and those services will see that you followed the link. They never include anything you entered.
We don’t receive any of this, and we can’t recall it. Once you’ve shared something, it’s covered by the privacy policies of the app you used and whoever receives it.
What the web host may see
Like any website, the company hosting this site may briefly keep standard server logs, such as IP addresses and which pages were requested, to keep it running and secure. These logs never contain what you enter, because that never leaves your browser. Your calendar, spreadsheet and backup files are created on your device.
Links to other sites
Source links go to other organisations, such as the NHS. Those sites have their own privacy policies. We don’t pass any information to them.
Contact
Questions about privacy: privacy@whyismyperiodlate.com
Last updated 2 November 2026.