This page aggregates measured, corroborated evidence: donors' iPhones recorded apps contacting this domain, every claim below was reported by separate accepted donations and published under a human verdict (later rows for an approved app inherit its verdict). A contact is a measurement, not an accusation — it does not show what data was sent.
gdx-api.costco.com
classified as first-party · 2
What our research panel found AI-drafted · human-reviewed
We ask several independent AI models the same question and publish their answers separately — cross-vendor agreement is evidence against fabrication, and disagreement is worth seeing. 3 of 3 models answered, overall confidence high. A human reviewed this domain's claims before anything here published.
Anthropic Claude — first-party
gdx-api.costco.com is a subdomain of costco.com, the app publisher's own domain, so this is first-party app infrastructure (likely an API endpoint); I do not know the specific function of the 'gdx' service. Contact with the developer's own backend is inherent to the app's function and consistent with the declared collection of app interactions and diagnostics, so nothing here implies an undisclosed data flow.
OpenAI — first-party
The domain is a subdomain of costco.com and most likely belongs to Costco for app API functionality. The provided privacy label already declares several relevant app-use and diagnostic data categories, and the contact alone does not establish an uncovered data flow.
Google Gemini — first-party
gdx-api.costco.com is a first-party subdomain belonging to Costco Wholesale. Contacting a first-party domain for app operations does not indicate an undisclosed third-party data flow.
Apps measured contacting this domain
| App | Label gap | Donations | Contacts | Seen |
|---|---|---|---|---|
| Costco Wholesale | — | 4 | 8 | 2026-07-28 → 2026-07-29 |
The corpus grows one report at a time: donate your App Privacy Report — anonymous by design.
Think something here is wrong?
Evidence and research improve when people push back. Tell us what to re-check — a misattributed domain, an outdated classification, a claim about your own app — and a human will review it. Responses can take up to 30 days.