Open Safari, go to Safari > Settings > Privacy, click Manage Website Data, and you will usually see a longer list than you expect: dozens or hundreds of domains, some holding a few kilobytes and a handful holding hundreds of megabytes each. That second group is often webmail, a web-based code editor, a project management tool, or anything else you leave open in a tab for hours at a time. This panel, not the files sitting under ~/Library/Safari or ~/Library/Caches, is the correct place to deal with it. Safari treats those on-disk files as its own internal state, and it does not expect anything outside itself to touch them. This article covers what actually accumulates, how to clear it per site or all at once, and what "Remove All" does and does not affect.

What Manage Website Data actually lists

Each row in the list represents one site's origin, and the size next to it is the sum of several different kinds of storage Safari keeps on that site's behalf:

  • Page cache — recently loaded HTML, CSS, JavaScript, and images, kept so the next visit loads faster.
  • Cookies — small pieces of state, usually tiny individually but numerous.
  • Local Storage and IndexedDB — structured data a site writes deliberately, often used for drafts, offline queues, or app state.
  • Service Worker caches — files a site's Service Worker has downloaded so the site keeps working (or loads instantly) without a network round trip.

The last category is the one that surprises people. A webmail client or a browser-based editor that has been engineered to work offline will often pre-cache a meaningful slice of its own application code and, in some cases, your data, through a Service Worker. That is by design on the site's part, and it is legitimate — but it means a single origin you visit daily can genuinely account for several hundred megabytes, which is not obvious from casually browsing the list.

Why the settings panel, not the files on disk

Safari's cache and history are not simple flat files you can safely delete or edit while the browser is running. They are backed by internal databases and are read and written continuously as you browse. You can look at their size for curiosity's sake:

du -sh ~/Library/Safari
du -sh ~/Library/Caches/com.apple.Safari

but going further than looking — deleting or editing anything inside those folders directly — risks putting Safari into an inconsistent state: broken history, missing favicons, or a browser that needs to rebuild its internal indexes from scratch on next launch. None of that is a reasonable trade for space you can free through the supported UI in a few clicks. Manage Website Data exists specifically so you never have to touch those files yourself.

Clearing one site versus clearing everything

The panel supports two different actions, and they serve different purposes.

To clear a single site, select its row and click Remove. This is the right move when you have spotted one large entry — say, a web app you tried once and never returned to — and want to reclaim its space without disturbing anything else. Because it is scoped to one origin, it will also sign you out of that specific site, since session cookies are stored alongside everything else.

To clear everything, use Remove All. This is a heavier operation, and it is worth understanding what it touches before running it: it clears cache, cookies, and stored data for every site in the list, which will sign you out of every site you were logged into through Safari. Apple's own description of this feature has shifted in wording across macOS releases, so rather than asserting exactly what it does or does not include on your specific version, the safer approach is to read the confirmation text Safari shows you at the moment you click it — it names what will be removed for the OS version you are actually running.

What generally survives a website data clear

In practice, clearing website data through this panel is a narrower operation than clearing Safari entirely. It targets data that sites have stored about themselves, not settings that belong to Safari or to your account:

  • Saved passwords, stored separately in the Keychain, are typically unaffected.
  • Bookmarks and Reading List items are a separate data structure and are not part of website data.
  • Browsing history is tracked separately from site storage, though the two are sometimes cleared together depending on which menu you use.

Again, treat the specific wording in your version of macOS as authoritative rather than assuming these hold in every release. Apple has changed privacy controls before, and it will again.

Why it grows without you noticing

Nobody sits down intending to accumulate hundreds of megabytes of Safari website data. It happens as a side effect of ordinary browsing: every site you log into leaves cookies, every site with offline support leaves Service Worker files, and every rich web application — a document editor, a design tool, a project tracker — leaves IndexedDB records that grow the longer you use it. None of this gets cleaned up automatically, because Safari has no way to know which of it you still care about. A site you used heavily for a single project six months ago and never opened since is, from Safari's point of view, indistinguishable from one you use every day. The data just sits there until you look.

That is also why periodically opening Manage Website Data and sorting by size is worth the two minutes it takes. It is one of the few places on a Mac where "old and forgotten" and "large" reliably line up.

Conclusion

Safari's website data is not a mystery once you know where to look, and clearing it does not require touching a single file yourself. The panel exists precisely so that the browser can manage its own storage safely while still giving you a real answer about where the space went and a real way to reclaim it, site by site or all at once.

We built VolumeLens because we needed the rest of a Mac's storage — the parts no browser panel can show you, spread across ~/Library, developer tools, and forgotten project folders — to be just as legible as Safari's own settings make website data. It scans your drive, shows every folder sized honestly, and only ever moves things to the Trash after you have reviewed what is being removed. You can download it and see, in a few minutes, what else on your Mac has been quietly growing the same way Safari's website data does.