How does DuckDuckGo’s Fireproofing work under the hood and what data types it preserves?
Executive summary
DuckDuckGo’s Fireproofing is a selective exception to the browser’s one‑tap “Fire Button” data purge: sites placed on the Fireproof list retain certain first‑party artifacts so users stay signed in and site features continue to work, while the rest of browsing data is still cleared on demand [1] [2]. Multiple independent reviews and how‑to guides describe that the preserved items are primarily cookies and related first‑party storage; other data like history, cached files, and open tabs continue to be removed by the Fire Button [3] [4] [5].
1. What Fireproofing does at a glance — exception, not a full whitelist
Fireproofing creates a site‑specific exception to DuckDuckGo’s global “clear everything” action so that essential site functionality survives a Fire Button purge, a behavior DuckDuckGo frames as preserving sign‑in state and other helpful data [1] [6]. The feature is presented to users in the flow of signing into a site or via the app UI, where users can add or remove sites from the Fireproof list [2] [7]. DuckDuckGo’s documentation and app messaging emphasize that this is a deliberate, limited tradeoff: it preserves what’s necessary to stay logged in without turning off the browser’s wider tracker protections [1].
2. The technical surface — cookies and first‑party storage are the primary artifacts
Public reporting and technical writeups consistently identify cookies — especially first‑party cookies — and related site storage as the core data types Fireproofing preserves, which is why users remain signed in after clearing other data [1] [3] [6]. Forensic testing of the Android app shows the cookies database is an artifact that remains for fireproofed sites, and DuckDuckGo blocks third‑party cookies by default so the saved cookies will generally be first‑party in nature [3]. Guides and reviews reiterate that the Fire Button normally clears cookies, cache, tabs, and history, and that Fireproofing exempts selected sites from cookie deletion [5] [4].
3. Where the preserved data lives — app/WebView storage and the app database
On Android, DuckDuckGo’s browser uses the system WebView engine, and investigators have found the app’s databases (for example app.db) and the WebView/SQLite cookie stores as places where Fireproof artifacts appear, meaning the preservation is implemented at the app storage layer rather than by altering web servers or cookies themselves [4] [3]. How DuckDuckGo maps a site to its preserved cookies and storage — and the exact on‑disk formats — has been documented by third‑party reviewers and forensic bloggers, but the company’s help pages describe the feature conceptually rather than exposing low‑level code in the materials quoted here [1] [3].
4. What Fireproofing does not preserve — limits and privacy tradeoffs
Multiple sources state clearly that Fireproofing does not prevent the Fire Button from clearing browsing history, cache, or open tabs [3] [5], so users still get session‑level privacy for most artifacts while retaining login state for selected sites [6]. DuckDuckGo continues to block third‑party trackers and forces HTTPS where possible, so fireproofing is not a blanket surrender of privacy controls — it’s a narrowly scoped persistence of first‑party data to preserve usability [1] [4]. Reviewers and privacy analysts have noted this is a pragmatic compromise that can leave forensic traces and is less “strict” than complete ephemeral browsing modes, a point critics raise about residual artifacts for fireproofed sites [4] [3].
5. User experience and implementation notes — how users interact with the feature
Users can enable Fireproofing through the app UI when signing into sites or by using menu options to add/remove sites, and settings include management of the Fireproof list and options around clearing on restart [2] [1]. Community guides and help pages describe the simple UX: enable, sign in, accept prompt to fireproof, and the browser will retain that site’s login cookies across Fire Button purges [2] [7]. DuckDuckGo frames this as a user‑controlled convenience that preserves “essential site functionality” while keeping broader tracker protections in place [1].
6. Open questions and disciplinary caveats
The sources make clear what Fireproofing preserves in practice — mainly first‑party cookies and related storage — and where it does not, but they do not provide a complete, line‑by‑line description of the underlying open‑source implementation in this set of documents; DuckDuckGo references its code and protections but the precise internal mechanics beyond app storage and WebView behavior are not exhaustively covered here [1] [3]. Independent reviewers have demonstrated the practical effects and artifacts, and alternative viewpoints emphasize the tradeoff between convenience and leaving persistent artifacts that may be relevant to privacy or forensic analysis [3] [4].