CoreOS — your whole work life, in one calm workspace.
CoreOS is a personal productivity app for the work that never fits a single tool — tasks and subtasks, follow-ups you can't afford to drop, a real calendar, your contacts and Notion-style notes. It runs in your browser, opens instantly, works offline, and backs your workspace up to your own Google Drive so a lost device or a cleared browser never means lost work.
Everything a busy day needs — nothing it doesn't.
Each part of CoreOS is built to feel instant and get out of your way. They also talk to each other: link a task, a follow-up, an event or a note to the same space or contact and it shows up everywhere it should.
Tasks that manage their own status
Break work into subtasks and let CoreOS keep the state honest: tick a subtask and the task moves to In progress on its own. It's only Done when you say so — never before. Priorities, due dates and search included.
Follow-ups you never drop
Track everyone you're waiting on — by email, call, message or meeting — with a due date and a clear overdue view. The moment a reply lands, mark it done and line up the next step in the same chain.
A calendar that actually repeats
Month, week, day and schedule views with all-day events, colour coding and proper recurrence — daily, weekly, monthly or custom. Edit one occurrence, this-and-future, or the whole series, just like you'd expect.
Contacts with tags & bulk actions
Keep the people you work with in one place, tag them, and add many at once — paste a CSV or fill several at a time. Select a group and apply tags in bulk. Every task, note and event links back to them automatically.
Notion-style notes & docs
A real block editor — headings, lists, to-dos, toggles, callouts, tables, code, bookmarks and multi-column layouts. Slash commands, drag to reorder, folders, page locking and full undo/redo. Great on desktop and mobile.
Spaces & workspaces
Group your work into spaces — clients, renewals, ops — and split unrelated worlds into separate workspaces that keep their own data. See a live dashboard of what's overdue, due today and happening now.
Built to feel instant, everywhere.
CoreOS is a single, tidy web app that opens straight from your browser — no loading spinners, no setup. Install it to your home screen or dock and it behaves like a native app, online or off.
- Works fully offline. Everything is saved on your device and keeps working with no connection.
- No lock-in. Export everything to a portable JSON file any time, and import it back just as easily.
- Light & dark. A calm, readable interface that follows your system theme or your choice.
- Seamless updates. New versions install quietly in the background — one click to refresh.
Open the app
Head to coreos.zentracker.in/app — it loads instantly, right where you left off.
Capture as you go
One tap adds a task, follow-up, event, contact or note — linked to the right space.
Stay ahead
The dashboard surfaces what's overdue, due today and happening now, per day.
Keep it safe
Your workspace backs up automatically to your own Google Drive — and you can export a JSON backup whenever you like.
Sign in once. Your data, on every device.
Signing in with a one-time email code is required to use CoreOS — no passwords, no social logins. And your workspace now backs itself up to your own Google Drive, so a lost phone or a cleared browser stops meaning a lost workspace. Your notes still never pass through us.
Email sign-in with a one-time code
A passwordless sign-in: enter your email, receive a 6-digit code, and you're in — it verifies the moment you type the last digit. No passwords to remember and no social logins, just a code in your inbox. It's required to use CoreOS, and it's live today.
Backup to your own Google Drive
CoreOS keeps a JSON backup in a private, app-specific folder inside your Google Drive — the hidden App Data area only CoreOS can see. Connecting an account is also required, so every workspace has somewhere to come back from. It's live today.
Yours, by design
CoreOS is built around a simple promise: your workspace belongs to you. It's stored on your device first, and cloud backup lands only in your own Google Drive — written by your browser, never through a CoreOS database.
We don't sell or share your data
No advertising, no data brokering, no reading your notes.
You can leave any time
Export a full JSON backup, or revoke access in one click.
Privacy isn't a setting. It's the foundation.
Most tools ask you to trust that they'll behave. CoreOS is designed so you don't have to: the app runs on your device, your data stays with you, and cloud backup writes to a Google Drive folder scoped so tightly that CoreOS can only ever touch the files it created itself.
- Email is used only to sign you in and secure your account.
- Drive sync uses the App Data folder — invisible to other apps and to us.
- Our use of Google data follows the Limited Use requirements in full.
Bring the calm to your day.
Open CoreOS and capture your first task, follow-up or note in seconds. No passwords, no credit card, no wait.