Privacy policy

Last updated: September 28, 2026

Histomap is an interactive history atlas operated by Siwei Ma at histomap.online. For privacy questions or a data deletion request, contact siweima3614@gmail.com.

Information used by the website

You can browse the atlas without an account. If you sign in, Clerk manages your account and session. Google sign-in supplies your account identifier, email address and basic profile, such as your name and profile image, to Clerk for authentication. Histomap requests no access to your Gmail messages, Google Drive files or contacts.

When you save a power estimate, the database stores your Clerk user ID, the historical year, your submitted values, a revision number and an update timestamp. We use this information to retrieve and update your contribution and calculate community estimates. The public community API returns combined estimates and contributor counts, not user IDs or individual account profiles.

Storage and service providers

Render hosts the website, Supabase stores contributions, and Clerk provides authentication. Google handles Google sign-in. These providers process information needed to deliver their services, which may include IP addresses, browser information and operational or security logs. Data may be processed outside your country.

Authentication uses cookies or similar browser storage. The website also remembers your language preference in local storage. Clearing browser storage can remove that preference and sign you out.

Your choices and retention

You can replace or withdraw saved contributions through the website. Withdrawal removes the submitted values from community calculations; the user ID, year and revision record remain to prevent stale updates. Deleting a Clerk account does not automatically remove its contribution records. Contact the address above to request deletion of your account and associated contributions. We may need to verify account ownership before acting.

Account and contribution records remain until removed. Hosting logs and backups follow the relevant provider's retention settings and may persist after removal from the active database. We do not specify a guaranteed deletion time for provider backups.

Use and disclosure

We use account information to operate login and contribution features, maintain security and respond to support requests. We do not sell personal information or use Google account information for advertising. Information is shared with the service providers described above as needed to operate the website, or when required by law.

Changes

Updates to this policy will appear on this page with a revised date.