The Browser Database Nobody Told You About
The problem is that IndexedDB has no expiry mechanism. Data written to it persists indefinitely until the website explicitly deletes it or the user manually clears it. Unlike cookies, it's not sent with HTTP requests, which means most cookie-blocking approaches at the network level don't affect it at all. And unlike cookies, most people have never once cleared it.
IndexedDB vs Cookies vs LocalStorage
Understanding the key differences explains why IndexedDB is the preferred backup identifier for sophisticated trackers.
Cookies
Expire automatically. Sent with every HTTP request. Blocked by many extensions and browser settings. The most scrutinised storage layer — and the most often cleared.
LocalStorage
No expiry. Not sent with requests. Holds up to 5–10MB per domain. Cleared by most modern privacy tools when specifically targeted, but often overlooked in manual cleanup.
IndexedDB
No expiry. Not sent with requests. Can store hundreds of megabytes. Supports complex structured data. Almost never cleared by users. Invisible in most browser privacy UIs.
How Trackers Use IndexedDB as a Backup Identifier
The tracking technique works as follows: on your first visit to a site using an advertising network, the network's JavaScript writes a unique identifier into IndexedDB (and simultaneously into cookies and LocalStorage). When you clear your cookies — which most people do occasionally — the identifier survives in IndexedDB. The next time you visit any site on the same network, the JavaScript reads back the IndexedDB value, re-creates the cookie from it, and your tracking profile is fully restored. You're re-identified within milliseconds of arriving.
How to Inspect and Clear IndexedDB Manually
In Firefox: press F12 → Storage tab → IndexedDB in the left sidebar. Same inspection and deletion is available.
The manual process reveals how much data is stored — it's often surprising. But it's not a practical privacy strategy: you'd need to repeat this for every site, every session, using developer tools most users have never opened. The real solution is automated clearing at the browser level.
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Why Automated Clearing Is the Only Practical Answer
Manual IndexedDB clearing through DevTools is educational but not scalable. Here's what a practical automated approach covers:
- 1Include IndexedDB in your cleaning profile: Broom Cookie Cleaner's data type selection includes IndexedDB alongside cookies and LocalStorage. Toggle it on once and it's cleared on every cleaning cycle.
- 2Clear all storage types simultaneously: The supercookie reconstruction chain breaks only when all layers are cleared at the same time. Broom's full-clean option covers cookies, LocalStorage, IndexedDB, and service worker caches in a single pass.
- 3Set a schedule that matches your risk tolerance: Hourly cleaning means a tracker's IndexedDB identifier has a maximum 60-minute lifespan. Daily cleaning is a reasonable baseline for most users.
- 4Use on-browser-close cleaning for convenience: Setting IndexedDB clearing to trigger when you close the browser means every new session starts without any residual identifiers from the previous one.
- 5Whitelist what you legitimately need: Some web apps — offline-capable email clients, note-taking apps — use IndexedDB legitimately for their core functionality. Broom's domain whitelist lets you preserve these while clearing third-party tracking stores.
Frequently Asked Questions
Common questions about browser cookies answered
Does clearing IndexedDB break websites?
For most sites, no. Sites that use IndexedDB for legitimate offline functionality (email clients, document editors, PWAs) will re-sync their data from the server on next load, similar to clearing cookies. The only effect is a slightly slower first load as data is re-fetched. Tracking identifiers don't recover — they require a new visit to the tracking network to be re-set.
Do all browsers have IndexedDB?
Yes. IndexedDB has been supported in Chrome, Firefox, Safari, and Edge for over a decade. It's a W3C standard and is universally available. There's no browser-specific variation in how trackers exploit it.
Is clearing IndexedDB different from clearing cookies in the browser settings?
Sometimes. Chrome's 'Clear browsing data' includes IndexedDB under 'Other site data' when using the Advanced tab. Firefox's equivalent includes it under 'Cookies and Site Data'. But many users clear only cookies and cache — which explicitly excludes IndexedDB. Always check what you're actually clearing, not just what the checkbox label implies.
How much storage can IndexedDB use?
Browsers allow IndexedDB to use a significant portion of available disk space — typically up to 20–50% of available storage, depending on the browser and OS. There's no per-site hard limit in most implementations. This means large web apps can write substantial amounts of data, and accumulated IndexedDB across many sites can become a meaningful disk space consumer over time.
