This Privacy Policy explains what information CoreOS collects, how we use and protect it, and the choices you have. CoreOS is a local-first application: your content lives on your own device, and cloud sync goes only to a private folder in your own Google account — your browser talks to Google directly, so your workspace never passes through our servers. We wrote this policy to be read, not skimmed — but if anything is unclear, contact us at the address in section 11.
What is required to use CoreOS
Email sign-in. CoreOS runs on your device, and — as of 23 July 2026 — email sign-in is required to use it: you verify your email address with a one-time code, and the first time you sign in we ask for your name and date of birth to create your account. The information processed on our servers is limited to those account details and your sign-in timestamps (sections 3.2 and 7). Your workspace content still never leaves your device unless you export it yourself.
Google Drive backup. Connecting your Google account is now also required, so every workspace has a recoverable backup rather than a single copy that disappears with the device. This runs entirely inside your browser: your backup is written directly to a private, app-only folder in your own Google Drive and never passes through our servers. Sections 3.3 and 5 describe exactly what this involves.
Contents
1Who we are
CoreOS (“CoreOS”, “the app”, “we”, “us”, or “our”) is a personal productivity application operated under the ZenTracker.in brand. The marketing site lives at coreos.zentracker.in and the application at coreos.zentracker.in/app. This policy applies to both.
CoreOS is designed as a local-first product. The application runs in your web browser (including as an installed Progressive Web App), and your workspace — spaces, contacts, tasks, follow-ups, events, notes and tags — is stored on the device you use, in your browser’s local storage. We do not operate a central database of your workspace content.
2Scope of this policy
This policy covers the CoreOS website and application. It describes the features that are available today — the local-first app, JSON export/import, email sign-in, and backup to your own Google Drive.
A change worth stating plainly. Sign-in and Drive backup were previously described here as optional additions; they are now requirements. Both are live and required as of 23 July 2026: you verify an email address with a one-time code, and you connect a Google account so your workspace is backed up to your own Drive. Requiring these makes your workspace recoverable when a device is lost or its browser storage is cleared, which local-only storage cannot guarantee.
CoreOS is a general-purpose productivity tool and is not directed at children under 13 (or the minimum age of digital consent in your jurisdiction). We do not knowingly collect personal information from children.
3Information we collect
3.1 Content you create (stored on your device)
Everything you enter into CoreOS — tasks and subtasks, follow-ups, calendar events, contacts, notes and resource pages, spaces, tags and workspace settings — is stored locally in your browser. This content remains on your device unless you explicitly export it, or turn on cloud sync (see section 5). We do not transmit this content to our servers.
3.2 Account information
To create your account and sign you in, we collect your email address, your name and your date of birth, together with a record of authentication events (for example, the time a one-time code was requested and verified). When you connect Google Drive backup, we also record the email address of the Google account you connected — this is the association described in section 5.2 that lets each of your devices find the same backup, and it is the only Google account information stored on our side. You provide your name and date of birth once, the first time you sign in, and both are required to create an account. We do not ask for or store a password. These account details are kept in a private spreadsheet that only the operator of CoreOS can access; your workspace content is never part of it. Because sign-in is required to use CoreOS, this applies to every user.
3.3 Google account information
Connecting a Google account is required in order to use CoreOS. The limited Google user data involved is described in sections 5 and 6. Note that this connection runs entirely inside your browser: we receive neither your Google credentials nor the contents of your backup.
3.4 Technical & diagnostic data
Like most websites, our hosting and content-delivery provider may process basic technical information required to serve the site securely — such as your IP address, browser type and request logs. This is used for security, abuse prevention and reliability, and is not used to profile you or build an advertising identity. CoreOS does not run third-party advertising trackers.
4How we use information
We use the limited information we process only to operate CoreOS. Specifically, to:
- run the application and store your workspace on your device;
- authenticate you and keep your account secure (email sign-in);
- back up and restore your workspace to and from your Google Drive;
- maintain the security, integrity and reliability of the service;
- respond to your support requests; and
- comply with legal obligations.
We do not sell your personal information, we do not use your content for advertising, and we do not use your CoreOS content or Google user data to train machine-learning or AI models.
5Google user data & Drive sync
Connecting a Google account is required to use CoreOS, so that every workspace has a recoverable backup rather than a single copy that disappears with the device. You connect through Google’s official OAuth consent screen and can see and approve exactly what access is requested. We request the narrowest scope that makes backup possible, and nothing more.
5.0 Your browser talks to Google directly
Drive backup is implemented entirely in the front end. Your browser authorises with Google and reads and writes the backup file itself; the data path is your device ⟷ Google, with no CoreOS server in the middle. Concretely, this means:
- your workspace content is never transmitted to, processed by, or stored on any CoreOS or ZenTracker server;
- your Google access tokens stay in your browser — we never receive or hold them;
- we operate no sync service, so there is no server-side copy of your data to breach, subpoena, or mishandle; and
- if we shut CoreOS down tomorrow, your backup keeps existing in your own Drive, because it was always yours.
This is a deliberate design choice. Running sync from the front end also keeps our operating costs near zero, which is part of how CoreOS stays what it is.
5.1 What we access
| Scope requested | Why CoreOS needs it |
|---|---|
.../auth/drive.appdata |
To create and maintain a single backup of your CoreOS workspace inside the hidden, application-specific “App Data” folder of your Google Drive. This folder is only accessible to CoreOS. |
.../auth/userinfo.email |
To confirm which Google account your backup belongs to, so the right workspace is restored on each device. |
.../auth/calendar |
Optional, and only if you switch on calendar sync. To list the calendars on your Google account and to read and write events on the calendars you choose to link, keeping them in step with a CoreOS workspace both ways. Since 2 August 2026 this replaces the narrower calendar.app.created scope, which could only ever reach a calendar CoreOS had made itself — see section 5.5. |
5.2 What the App Data folder means for your privacy
The Google Drive App Data folder (also called the “application data folder”) is a special hidden area of your Drive reserved for a single application. Because CoreOS uses the drive.appdata scope:
- CoreOS can only read and write files that CoreOS itself created in that hidden folder;
- CoreOS cannot see, list, open, modify or delete any of your other Google Drive files, folders, photos or documents;
- the backup does not appear in your normal Drive view and does not clutter your Drive; and
- other apps cannot read the CoreOS backup, and CoreOS cannot read other apps’ data.
5.3 What we store there, and where it lives
CoreOS writes a backup of your workspace (the same portable JSON structure you can export manually) into that hidden folder in your own Google Drive. Your workspace content is stored in your Google account, which you control — not on CoreOS servers. We keep, at most, the minimal account record needed to associate your CoreOS account with the correct Drive backup (see section 3.2).
5.4 How the data is used
Google user data obtained through these scopes is used solely to provide the backup-and-sync feature you requested: writing your latest backup, and reading it back to restore your workspace on your devices. It is never used for any other purpose.
5.5 Google Calendar sync (optional)
Since 29 July 2026 you may optionally connect a workspace to Google Calendar from the Calendar page. Unlike sign-in and Drive backup, this is entirely optional — CoreOS works exactly as before if you never switch it on.
Changed on 2 August 2026 — please read. Calendar sync previously used the calendar.app.created scope, under which CoreOS created a calendar of its own and could not reach any other calendar on your account. Because that also meant your own calendars could never appear in CoreOS, sync now uses the broader .../auth/calendar scope. CoreOS can therefore now access all calendars on the Google account you connect, and this is a genuine widening of access. You will be asked to grant it explicitly, and you can decline or revoke it at any time without affecting the rest of CoreOS.
What calendar sync does:
- On connecting, CoreOS lists the calendars on your account and you tick the ones to follow. Calendars you do not tick are not read and not written to.
- Followed calendars sync both ways. You nominate one of them as the calendar new CoreOS events are published to.
- Calendars shared with you read-only are pulled into CoreOS for display and are never written to.
- Only events on a calendar you have linked are sent to Google. Events on the CoreOS-local calendar — including demo data and JSON imports — are never uploaded.
- Each workspace connects to one Google account, and different workspaces may use different Google accounts.
- Syncing is manual: it runs when you press Sync, never on a timer and never in the background. Deleting an event on either side deletes it on the other.
- Like Drive backup, this runs entirely in your browser — calendar data travels device ⟷ Google and never reaches a CoreOS server. Links you add in CoreOS between an event and a Space or Contact stay on your device; Google never receives them.
- The access is used solely to provide this sync. Calendar data is never used for advertising, profiling, analytics, model training, or transferred to anyone.
5.6 Turning it off & deleting the backup
You can disconnect Google Drive at any time from within CoreOS, and you can revoke CoreOS’s access to your Google account at any time from your Google Account settings at myaccount.google.com/permissions. You may also delete the CoreOS backup file directly. Deleting the backup or revoking access does not delete the copy of your workspace already stored locally on your device.
Calendar sync can be disconnected separately, from the Calendar page in the app, and individual calendars can be un-ticked at any time without disconnecting. Disconnecting stops the two sides following each other but deletes nothing: your events remain both in CoreOS and in your Google calendars, which are left exactly as they are.
6Google API Services Limited Use disclosure
Limited Use commitment
CoreOS’s use and transfer of information received from Google APIs will adhere to the Google API Services User Data Policy, including the Limited Use requirements.
In line with those requirements, CoreOS specifically commits that Google user data accessed through the scopes above is:
- used only to provide and improve the user-facing backup and sync features described in this policy;
- never transferred or sold to third parties for advertising, marketing, resale, or the building of profiles or data brokerage;
- never used to serve advertisements; and
- never read by humans, unless (a) you have given explicit consent to view specific data (for example, to help with a support issue), (b) it is necessary for security purposes such as investigating abuse, or (c) it is required to comply with applicable law, or the data has been aggregated and anonymised.
We also commit not to use Google user data to develop, improve or train generalised or non-personalised AI and/or machine-learning models.
7Email & authentication
CoreOS uses a passwordless, one-time-code sign-in. When you sign in, a verification code is sent to your email address using Loops.so, a transactional email provider acting as our processor. Loops.so processes your email address and the message content solely to deliver these emails on our behalf; it is not permitted to use your address for its own marketing. We use your email address to identify your account, deliver sign-in codes, and send essential service notices. We do not send marketing emails without a separate opt-in.
7.1 Where the check happens
Issuing and verifying sign-in codes is the one part of CoreOS that requires a server, because a code a browser checks against itself proves nothing. That step runs on Cloudflare Pages Functions, on the same infrastructure that already serves this site. The function receives your email address and the code you entered, confirms they match, and returns a session — nothing more.
It is worth being precise about the boundary this creates, because it is the only one:
- your email address, name, date of birth and sign-in events are processed and stored server-side (in a private spreadsheet only the operator can access);
- your workspace content is not — it never reaches that function, or any other server we run;
- Drive backup bypasses our infrastructure completely (see section 5.0).
8Storage, security & retention
Local storage. Your workspace is stored in your browser on your device. Clearing your browser storage, or uninstalling the app, will remove that local copy — which is why Google Drive backup is required, and why an occasional JSON export is a useful second copy.
Security. The site and app are served over encrypted HTTPS connections. Access to your Google Drive backup is authorised through Google’s OAuth and stored using access tokens rather than your Google password, which we never see. We apply reasonable technical and organisational measures to protect the limited account data we hold, including rate-limiting sign-in attempts by network address to deter abuse. No method of transmission or storage is ever perfectly secure, but we work to protect your information and limit what we hold in the first place.
Retention. We retain account information (such as your email) for as long as your account is active. If you delete your account or ask us to, we delete the associated account record. Backups you have stored in your own Google Drive remain under your control and are deleted when you delete them or revoke access. Local content is retained on your device until you remove it.
9Sharing & disclosure
We do not sell or rent your personal information. We share information only in these limited situations:
- Service providers (processors) who help us run CoreOS — our website host and CDN, Cloudflare (which also runs the sign-in function described in section 7.1), our email provider Loops.so, and Google (which hosts the private spreadsheet where your account record — email, name and date of birth — is stored) — and only to the extent needed to perform their function on our behalf.
- Google, as the provider of the Drive storage you connect. Because that connection is made directly by your browser (section 5.0), this is not a disclosure by us at all: we never hold the data in order to pass it on.
- Legal & safety: where we reasonably believe disclosure is required by law, or necessary to protect the rights, safety or property of our users, the public or CoreOS.
- Business transfers: if CoreOS is involved in a merger, acquisition or asset sale, information may be transferred, and we will notify affected users and honour the commitments in this policy.
10Your rights & choices
You are in control of your data:
- Access & portability: export your entire workspace to a portable JSON file at any time from within the app.
- Deletion: erase a workspace from within the app, delete your Drive backup, and request deletion of your account record by contacting us.
- Withdraw Google access: disconnect Drive in the app, or revoke access at myaccount.google.com/permissions.
- Regional rights: depending on where you live (for example under the EU/UK GDPR or similar laws), you may have rights to access, correct, delete, restrict or object to processing of your personal data, and to lodge a complaint with your local data-protection authority. Contact us to exercise these rights.
11Changes & contact
We may update this policy as CoreOS evolves. When we make material changes, we will revise the “Last updated” date above and, where appropriate, provide a more prominent notice. Continued use of CoreOS after an update means you accept the revised policy.
If you have questions about this policy or your data, or wish to exercise any of your rights, contact us at:
Email: contact@zentracker.in
Website: coreos.zentracker.in