What measurable differences exist between DuckDuckGo's mobile app and desktop extension in third-party fingerprinting tests?
Executive summary
Public reporting and DuckDuckGo’s own documentation show the company applies similar anti-fingerprinting strategies in both its mobile app and desktop browser extension—blocking many third‑party trackers, preventing fingerprinting scripts from loading, and overriding browser APIs used for fingerprinting—but independent, quantified third‑party test data directly comparing the mobile app versus the desktop extension are not provided in the available materials, leaving measurable differences largely unreported [1] [2] [3].
1. What “third‑party fingerprinting tests” are trying to measure
Third‑party fingerprinting tests generally try to quantify how much identifying information a site or tracking script can collect (APIs exposed, canvas/webgl outputs, screen and device attributes, loaded third‑party scripts, request headers and cookies), and then estimate uniqueness or trackability of that data; reporting and help pages define fingerprinting as combining browser and device data to create identifiers that follow users across sites [3] [1].
2. DuckDuckGo’s stated protections across platforms
DuckDuckGo says it blocks many fingerprinting scripts before they load with “3rd‑Party Tracker Loading Protection” and that it “overrides many of the browser APIs used for fingerprinting” to return no or less useful information, a claim presented as applying to its web protections broadly [1]. The company also promotes that its extension “blocks most” hidden third‑party trackers on top sites and forces HTTPS where available, framing the extension and app as delivering similar protections [2].
3. Signals from reporting and developer discussion about platform behavior
TechCrunch reported DuckDuckGo’s denial of claims it uses fingerprinting to track users and said the company is building detection into both the mobile app and browser extension; DuckDuckGo engineers noted use of APIs like getBoundingClientRect() for layout purposes and suggested that such API calls can trigger fingerprinting blockers as false positives [3]. Meanwhile, user reports and a GitHub issue on DuckDuckGo’s Android repo document that some third‑party tests (e.g., EFF’s Cover Your Tracks) still show a “unique” fingerprint when using the mobile browser, indicating residual fingerprint surface in real‑world tests [4].
4. What measurable differences are actually reported (and what is not)
Available sources do not provide side‑by‑side numeric test results (no percent reductions in entropy, uniqueness scores, or counts of blocked fingerprinting scripts comparing mobile app vs desktop extension) — DuckDuckGo’s public pages describe capabilities qualitatively (blocking and API overrides) but offer no published metrics that quantify platform gaps [1] [2]. TechCrunch documents a specific API (getBoundingClientRect) that can trigger fingerprinting flags and that DuckDuckGo uses it for layout, suggesting one concrete behavioral difference in how sites may perceive the client, but it does not translate into a measured change in trackability across platforms [3]. User‑reported tests on GitHub indicate that mobile users have observed uniqueness in fingerprint tests, which is a measurable outcome (uniqueness) reported anecdotally but not systematically or comparatively against the extension [4].
5. How to interpret these gaps and what agendas they reveal
DuckDuckGo’s public messaging emphasizes strong, cross‑platform protections and frames its design choices as avoiding “scorched earth” API blocking to preserve functionality while preventing tracking [1] [3]. Independent security researchers and extension vendors may be incentivized to highlight any remaining fingerprint surface as a credibility concern; conversely, DuckDuckGo has an incentive to stress that it does not fingerprint users and that any API usage that flags as “fingerprinting” is for legitimate functionality [3]. Given the absence of peer‑reviewed or reproducible comparative test data in the cited sources, definitive, measurable differences between the mobile app and desktop extension cannot be asserted from the available reporting [1] [4].
6. Practical takeaway and next steps for rigorous comparison
The public record shows functional parity in intent—blocking third‑party fingerprinting scripts and overriding APIs—but lacks quantitative, reproducible third‑party test comparisons; to obtain measurable differences would require controlled tests that expose both clients to identical fingerprinting suites (entropy/uniqueness scoring, API exposure logs, and counts of blocked scripts) and publish the results, something neither DuckDuckGo’s help pages nor the cited reporting provide [1] [3] [4].