Privacy
This page explains what this website records when you register for our data products, why we record it, what is published publicly, and how to have your data removed. It describes the site as it actually behaves — the registration form, the session cookie, the download log and the statistics shown on the Products page.
What we collect
Only what the registration form asks for, plus what a web server unavoidably sees:
- Account details — first and last name, e-mail address, country, institution, department, position type (student / postdoc / faculty / other), research field, and the products you register for.
- Technical records — the IP address and browser user-agent string of registration, login and download requests, kept for security auditing (abuse, credential sharing) and for the download log. The city-level user map is built first from the institution you entered; only where that cannot be placed is the IP address of your most recent registration used, matched locally against an offline GeoLite2 database on our own server. No IP address is ever sent to a third-party geolocation service. Page views are counted as an anonymous integer per URL; no per-visitor identifier is stored.
- Session cookie — a single first-party cookie
acm_session, set after you log in. It isHttpOnly(unreadable by JavaScript),SameSite=Lax, and expires after 30 days. There are no analytics, advertising or third-party cookies on this site.
Why we collect it
- To authorise downloads of data products whose terms ask us to know who is using them.
- To understand, in aggregate, which products are used and by whom — this is what the statistics on the Products page report, and what we mention in papers and progress reports.
- To keep the service working and to detect abuse.
We do not sell, rent or share your details, and we do not send newsletters.
What is published
Two things derived from registration records appear publicly, both aggregated:
- Counts — number of registered users, institutions and countries per product, plus the first and last registration date for each product. Dates are reported in Beijing time (UTC+8); they are shown as a range per product, never per person.
- A map of registered users — one dot per place, plotted at city-level precision (coordinates rounded to about 1 km). A dot’s location is taken from the registrant’s institution; the IP address is only used when the institution cannot be placed. Zoom in and each dot also names the institution(s) that registered from that place, taken from the affiliation field of the registration form. Where several people registered from the same institution in the same city, they are shown as one entry with a count.
The map never shows names or e-mail addresses, and it never links an institution to a person who registered. Individual names, e-mail addresses and institution–person pairings are not published anywhere.
Retention and your rights
- Account records are kept while the products are in service; download and login logs are kept for security auditing.
- You may ask us to show, correct or delete your registration at any time by writing to linjt@pku.edu.cn from the address you registered with. Deletion removes your account and its technical records; the aggregate counts are recomputed.
- If you are in the EU/EEA or the UK, the same request covers your rights under the GDPR; if you are in China, the same request covers your rights under the PIPL.
Third parties
- Map tiles. The maps on the Group and Products pages load tiles from AMap (AutoNavi) or Google Maps, so those providers see the IP address of visitors who scroll to a map. No other third-party service is contacted.
- Hosting. The site is served from a server operated by the research group at Peking University; no external CDN or cloud analytics is involved.
Changes
If this policy changes, the updated version will replace this page and the date below will move. Questions about anything here can go to linjt@pku.edu.cn.
Last updated: 2026-11-08.