Privacy policy

What Checkmate collects

Salted SHA-256 hashes of sender and recipient email addresses.
Gmail thread and message IDs.
The IP address, user agent and network (ASN and organization) of each tracking-pixel load.
A random per-install token, stored only as a hash on our server.
The time of each pixel load and of send, view and reply events (used to show, for example, "Read · 2:31 PM").
If you sign in (required to subscribe): your Google account ID (the sub value from Google sign-in; no email address is requested or stored), linked to your install token hash. If you subscribe, also your Stripe customer ID, subscription ID and subscription status.

Plaintext email addresses and email content never leave your browser. Only the data listed above is sent to our server.

Payments are processed by Stripe. No card data touches Checkmate.

Emails sent on the free tier carry a visible "Sent with Checkmate ✓✓" footer linking to https://checkmate.nimhq.com. Paid subscribers' emails do not.

Checkmate runs on Cloudflare (Workers, D1 and Pages).

Questions or deletion requests: [email protected]