Privacy
The short version: what you type stays in your browser.
What you type
Every calculation happens in your browser. Developer strengths, amounts, hair lengths, heights, dates and timer names are never sent to Satin Fern or anyone else. Apart from loading the site's own files, the pages make no network requests; the one exception is the page-view count described below.
What is stored on your device
Two things can be saved in your browser's local storage, only on the device you are using: your light or dark theme choice, and the dye timers (their names, lengths and finishing times) so that they survive a reload. They are never uploaded. “Back to the four starting timers” on the timer page removes the saved timers, as does clearing this site's data in your browser settings.
Sound, alerts and screen
The timer's chime is made in your browser with the Web Audio API and only after you tap Sound on. If you tap Alert me, your browser asks whether this site may show notifications; the notifications are created on your device and nothing is sent to a server. Keep screen on uses your browser's screen wake lock while the page is open.
Cookies, accounts and ads
There are none. There is no sign-up, no advertising and no tracking across other sites.
Page-view counts
The site uses Cloudflare Web Analytics, which our host Cloudflare adds to each page, to count page views. It does not use cookies or track you across sites, and it never receives what you type into the tools.
Links to other sites
Pages link to sources such as the FDA, the NHS, DermNet and the EU's legal database, to sister sites and to two recommended services, CleanTempMail and WebTraceCheck. Those sites have their own privacy policies, which apply once you follow a link.