The Storage Layer Most People Never Touch
This is exactly why sophisticated trackers use them. They're the persistence layer that survives the privacy cleanup most users actually perform.
The Three Hidden Storage Types
Here's what each one does and why it matters for privacy.
LocalStorage
A simple key-value store that persists across browser sessions with no expiry date. Stores up to 5–10MB per domain. Unlike cookies, it's never sent automatically to servers — but it can be read by JavaScript on any page from the same domain.
IndexedDB
A full client-side database with structured data support. Can store megabytes of complex data per origin. Used by web apps for offline functionality — and by trackers as a durable backup identifier that survives cookie deletion.
Service Workers + CacheStorage
Background scripts registered by websites that intercept network requests and manage a separate cache. Can store assets and run logic even when the page is closed. Persist until explicitly unregistered.
How Supercookies Work in Practice
A 'supercookie' or 'evercookie' is a tracking technique that stores an identifier in as many storage locations as possible simultaneously — cookies, LocalStorage, IndexedDB, cache, and more. When you clear cookies, the identifier still exists in LocalStorage. When you clear LocalStorage, it's reconstructed from the IndexedDB copy. Clear that, and a service worker cache or HTTP ETag restores it again. Each storage layer acts as a backup for the others.
Why This Matters Even If You're Not a High-Risk User
LocalStorage-based tracking is particularly relevant because it doesn't require cookie consent under most current interpretations of GDPR and CCPA — it's a grey area regulators haven't fully addressed. Trackers actively exploit this ambiguity.
The average user clears cookies once every few months. A supercookie can reconstruct itself and resume tracking within minutes of that cleanup.
Take Control of Your Privacy Today
Automatically manage and delete cookies with Broom Cookie Cleaner
How to Actually Clear All Storage Types
Effective storage cleanup requires clearing all layers simultaneously. Broom Cookie Cleaner covers the full stack:
- 1Cookies: The traditional tracking layer. Broom clears these with domain-level control — whitelist what you need, clear everything else.
- 2LocalStorage: Enabled as a toggle in Broom's cleaning profile. Cleared alongside cookies so supercookie reconstruction fails.
- 3IndexedDB: Also included in Broom's cleaning options. Removing it alongside LocalStorage breaks the backup-identifier chain.
- 4Service Workers: Broom can unregister service workers and clear their associated CacheStorage on each clean cycle.
- 5Schedule all of it together: The power of Broom is running these cleans simultaneously on a schedule. Supercookies depend on finding at least one intact storage layer — cleaning all layers at once removes that fallback.
Frequently Asked Questions
Common questions about browser cookies answered
Does LocalStorage affect page performance?
Not meaningfully. LocalStorage is synchronous and blocking by design, but most sites use it for small amounts of data. Clearing it may cause a site to lose your preferences on the next visit, but has no negative performance impact.
Can I see what's stored in LocalStorage?
Yes, but it requires developer tools. In Chrome or Firefox, open DevTools (F12), go to Application > Storage > LocalStorage. You'll often find tracking identifiers sitting alongside legitimate data like UI preferences.
Is clearing service workers safe?
Yes. Service workers are reinstalled the next time you visit the site. The only effect you'll notice is that Progressive Web Apps (PWAs) may need to re-cache their assets, causing a slightly slower first load.
Do privacy-focused browsers like Brave handle this automatically?
Brave and Firefox block some cross-site tracking at the network level, but they don't automatically clear LocalStorage or IndexedDB on a schedule. You still need to actively manage these — or use a tool that does it for you.
