Hollow Search privacy notice
Last updated: 6 October 2026
This notice covers search.projecthollow.com. Hollow Search is operated by Soulstack, the data controller, Office One, 1 Coldbath Square, Farringdon, London, EC1R 5HL, England. The Project Hollow privacy policy covers Hollow accounts and the rest of the suite.
Your searches
- We do not log your queries against you, your IP address or any identifier. We keep aggregate counts only (for example, searches per hour) to run and size the service.
- Your IP address is used briefly, in memory, to rate limit requests and stop abuse. Our hosting provider keeps standard request logs for security for a limited period.
- Results pages set no cookies of their own and load no analytics or advertising scripts.
- Your SafeSearch choice is stored in your browser only.
Pictures
On the Images tab your browser loads each thumbnail directly from Wikimedia (upload.wikimedia.org), not from us, so Wikimedia can see your IP address and the picture you asked for, as it can for any visitor to its sites. We ask for them anonymously and without telling Wikimedia which page you came from, so no cookie is sent to Wikimedia or stored from it and no page address is shared. Wikimedia’s own privacy policy applies to what it does with the request.
Maps and location
On the Maps tab your browser loads map tiles, fonts, styles and place-search index files directly from tiles.projecthollow.com. The Maps CDN receives your IP address and the map tiles and index shards requested. Place search runs in your browser against a public index; it requests shards derived from a short normalized query prefix or, for UK postcodes, the outward postcode area, rather than sending the full query to the Search engine. As with any map, the tiles requested can reveal the area you view to the CDN.
The “Show my location” control asks your browser for device location only after you press it. Hollow Search uses the returned coordinates in memory to move the map; it does not send them to the Search engine or save them. Subsequent tile requests can reveal the displayed area to the Maps CDN. Your browser may deny the request, and you can manage the permission in its site settings.
Map data includes OpenStreetMap data and UK Ordnance Survey Open Names data. Hollow Search displays the required attribution alongside map and place results.
AI answers
When Hollow AI writes an answer, the query and the text of the top results are sent to the AI model provider that generates it, which processes them on our behalf. Answers are cached for 24 hours under a one-way hash of the query; the query text itself is not stored. To protect answers from automated abuse, the results page uses Firebase App Check, which runs Google reCAPTCHA in your browser.
If you are signed in to Project Hollow, answers you ask for are counted against your account’s AI limits under the Project Hollow privacy policy. Signing in is never needed to search.
Lawful basis
We process this data on the basis of our legitimate interest in providing a working, secure search service (UK GDPR Article 6(1)(f)).
Pages in the index
The index holds public web pages, news headlines from publishers’ feeds and details of pictures on Wikimedia Commons (its titles, descriptions, categories and licences, never the pictures). If a result shows personal data about you that you want removed, use the report page. We review delisting requests, including requests under data protection law, and remove results where the law requires or the request is justified.
Your rights
You can ask us about any personal data we hold, and ask for it to be corrected or erased, by emailing search@projecthollow.com. You can also complain to the Information Commissioner’s Office at ico.org.uk.