Chrontab

A standalone Manifest V3 extension for Chrome, Edge, Brave, Vivaldi, and other Chromium browsers (Chromium 120+). Snooze a tab once or bring it back on a custom calendar schedule.

Install locally

1. Download Chrontab-1.1.1.zip from the latest release and extract it.
2. Open chrome://extensions (or edge://extensions).
3. Enable Developer mode.
4. Click Load unpacked and select the extracted folder containing manifest.json.
5. Pin Chrontab to the toolbar.

If you cloned the source repository, run the build commands below and load the generated dist folder instead. No account or server is required to use the extension.

Signed CRX package

The release also includes Chrontab-1.1.1.crx, a CRX3 package generated by Chrome and verified locally with its RSA signature and embedded manifest. Its stable extension ID is omkhbnimcklinkpbjmedhmoocjohfjlf.

Chrome restricts off-store CRX installation on Windows and macOS. Use the ZIP and Load unpacked for local development, or a browser/deployment policy that supports self-hosted CRX packages. See Chrome distribution documentation. To migrate from an unpacked installation with a different extension ID, export and import your Chrontab JSON backup.

To produce a future CRX:

pnpm build
pnpm pack:crx

The packager uses Chrome's native pack-extension command and keeps its signing key in the ignored .signing/chrontab.pem file. Back this key up privately outside the repository; reuse it to retain the same CRX identity. The key is never included in the extension ZIP/CRX or release uploads. Set CHRONTAB_SIGNING_KEY to use an existing private key and CHRONTAB_BROWSER to select a Chrome/Chromium executable. A newly generated key creates a different extension identity.

Appearance

Chrontab uses Material UI (MUI) theming, CssBaseline, and segmented appearance controls, with matching Material palette tokens across the dashboard, popup, and recurrence picker. Choose Light, Dark, or System in either page. The preference is saved locally, shared across open Chrontab pages, and restored before paint. System mode follows the operating system’s appearance. All dependencies are bundled in the extension; runtime use requires no CDN or network connection.

Design references: MUI showcase and MUI dark mode.

Snooze a tab

Open an HTTP or HTTPS page and click the Chrontab toolbar button. Use an hour, tomorrow at 9 AM, or a week as a shortcut, or choose a date and time. Select Repeat for the custom recurrence dialog, then Snooze this tab.

Chrontab saves the schedule before closing the original tab. It saves the URL and pinned state, not page content, forms, scroll position, login sessions, or unsaved work. Private/incognito tabs and browser-internal, file, and extension URLs cannot be snoozed.

Open the management page using the popup’s arrow, the Chrontab name, or the extension’s Options. You can also schedule a URL directly without closing a tab.

Calendar view

Choose Calendar on the dashboard to see a month of upcoming tab reopenings. Recurring wakeups are projected through the same rule engine used by the background scheduler. Move between months, return to today, toggle date-list overlays, select a day for its full agenda, or select a wakeup to edit the tab. Paused tabs are omitted. Projected dates may change when you edit lists or when delayed wakeups consume occurrences.

Date lists

Choose Date lists → New date list:

• Regional holidays: select a country, optional state/province and subdivision, holiday categories, and whether to include observed/substitute days.
• Workdays & hours: use the seven-day timeline to drag out blue time blocks, or select a block and edit its exact start/end. Multiple shifts per day are supported. Work blocks include their start and exclude their end. Split overnight shifts into two blocks at midnight; end time may be 24:00. Optional regional holidays are excluded automatically.
• Custom dates: add labeled single dates or inclusive ranges. Each entry can repeat annually or exclude dates from the list. Split annual ranges crossing New Year into two entries.

Regional and workday lists also accept date overrides. An included workday date can re-enable a holiday but still respects that weekday’s hours. Excluded overrides take priority. No country is assumed. You can keep several regional and work schedules.

Use View dates on any list to inspect a year of its dates and names. Lists assigned to a tab cannot be deleted until their references are removed. Editing a list recalculates assigned schedules without resetting completed occurrence counts; paused schedules stay paused.

Holiday data comes from the bundled date-holidays database, not a live Home Assistant connection. Data updates ship with extension updates. Its country/subdivision coverage and classifications can differ from Home Assistant’s Python holidays database. Lists support dates from 2000 through 2199. The packaged notices retain the data and code attribution.

Wake rules and exclusions

In a tab editor, open Calendar lists & date rules, enable Use date rules, and select conditions in nested All of (AND) or Any of (OR) groups. Assigned schedule means the tab’s selected date/recurrence. Each list is another selectable condition. A group can contain more groups. Add a separate Except when group for exclusions; matching an exclusion always prevents automatic opening.

For example: All of [Any of [Assigned schedule; Regional holidays]; Office hours], except Time off.

All matching dates use the tab’s chosen local start time. A work-hours condition must contain that time. The assigned-schedule condition follows the repeat interval; list conditions may add other dates through an Any group. Recurrence endings and occurrence counts apply to all resulting reopenings.

Date-list conditions conflict with Does not repeat: Chrontab displays a warning and disables saving until you select a recurrence or remove all date-list conditions. The worker and JSON import validate the same restriction. Skipped dates do not consume an occurrence, and dates are not shifted to the next workday. Exclusions and work hours are checked again for overdue automatic wakeups. Manual Open now remains an explicit override.

A live preview shows the next qualifying wakeups. Empty groups, missing lists, invalid hours, and no matching dates must be resolved before a schedule can be saved. Excessively broad/contradictory rules can reach the evaluation limit; simplify them when prompted. If a saved rule has no remaining matches after a list change, it is retained and paused with an explanation.

Custom recurrence

The picker follows Google Calendar’s layout: Repeat every N days/weeks/months/years, weekday buttons, and endings of Never, On a date, or After a number of occurrences.

• Weekly rules support several weekdays and intervals such as every two weeks.
• Monthly rules support the same date or the same ordinal weekday (for example, the second Tuesday).
• A missing calendar date is skipped: January 31 repeats on March 31, and February 29 repeats in leap years. Fifth weekday rules also skip months without that weekday.
• The start date is the earliest allowed occurrence. If it is not a selected weekday, the first matching weekday is used.
• End dates are inclusive. Occurrence counts include the first actual reopening.
• Open now consumes the pending occurrence; a recurring schedule continues from the following scheduled occurrence.
• Editing a schedule resets its start and completed occurrence count.
• Pause holds the schedule. Resuming an overdue schedule reopens it shortly.

Timing and recovery

Calendar rules follow the device’s local wall-clock time, including daylight saving changes. During a spring-forward gap, JavaScript moves the nonexistent time forward by the gap. In a repeated autumn hour, the earlier occurrence is used. Future dates follow the current device time zone; this version does not offer a fixed time zone per schedule.

Schedules persist in chrome.storage.local. The service worker recreates its next alarm on startup and whenever it starts. One alarm handles the whole queue. Missed recurring wakeups are combined into one reopening, then the next future calendar occurrence is scheduled. Missed dates do not consume extra occurrences.

The browser must be running to open tabs, and alarms can be delayed by device sleep or browser scheduling. Failed reopenings are kept and paused for a manual retry. As with browser extensions generally, an abrupt crash between opening a tab and saving the updated queue can reopen that tab again after recovery.

JSON backups

Use Export JSON on the management page. Import merges a Chrontab backup with the saved queue, skips existing IDs, validates the entire file before saving, and reports added/skipped counts. Importing an overdue schedule may open it shortly after import. Import preserves next wake times, repeat rules, completion counts, and paused state.

New exports use version 2, including date lists and nested conditions. Version 1 imports remain supported. Existing IDs are kept when merging; imported rules referencing an existing list ID use that existing list definition. Version 2 files have this envelope:

{
  "format": "chrontab",
  "version": 2,
  "exportedAt": "2027-01-01T12:00:00.000Z",
  "tabs": [],
  "dateLists": []
}

Limits: 5,000 schedules, 100 date lists, 2,000 date entries per list, and an 8 MB import file. Browser storage quotas still apply. Backups contain URLs and titles; keep them where you would keep bookmarks. Export backups before uninstalling, as uninstalling removes local extension storage.

Privacy and permissions

No analytics, remote scripts, website content access, external requests, or account sync. All interface icons and the application logo use official Pictogrammers Material Design Icons from the bundled @mdi/js package; the extension does not fetch favicons.

• activeTab: read the current page’s URL and title after you click the toolbar icon.
• storage: save schedules on this device.
• alarms: reopen tabs when due.

Icons

The application logo is MDI alarm-snooze, used unchanged in the interface and rasterized into the 16, 32, 48, and 128 px extension icons. Navigation, actions, appearance toggles, empty states, select arrows, calendar indicators, and search clearing also use MDI paths. Icons inherit the selected light or dark palette.

Run pnpm icons:generate to regenerate logo PNGs, the source logo SVG, and native-control indicators. pnpm build runs this automatically. See icons/LICENSE-MDI.txt for the icon license.

Development and verification

With Node.js 22.13+ or 24+, and pnpm 11.25.0 installed:

pnpm install --frozen-lockfile
pnpm build
pnpm check

Load dist as the unpacked extension after building. The source HTML files depend on the build step. Unit tests run through a portable Node launcher with America/New_York fixed as the time zone, so daylight-saving cases exercise real 23-hour and 25-hour days. Tests cover recurrence boundaries, DST behavior, validation, service worker scheduling, import merging, storage failures, and concurrent writes.

After loading unpacked, manually verify:

1. Snooze a disposable webpage for one minute from now; verify closure and reopening.
2. Create a weekly rule with several days and each ending option.
3. Edit, pause, resume, open now, and delete schedules.
4. Export, remove a schedule, and reimport the JSON; verify duplicates are skipped.
5. Close and reopen the browser after a wake time; verify one recovery opening.
6. Repeat in your other Chromium browser.

Browser checks use the declared Playwright development dependency and temporary isolated profiles. On Windows, they prefer an installed Edge; other platforms use Playwright Chromium. Set CHRONTAB_BROWSER to override browser discovery.

pnpm exec playwright install chromium
pnpm test:e2e

The two checks cover the actual loaded extension, recurrence creation, pause/resume, search and filters, themes, automatic alarms, weekly work blocks, nested conditions, calendar projection, and JSON backup restoration. Screenshots go to artifacts/. Browser fixtures use future dates so they do not expire. Popup rendering injects a sample current-tab result; real toolbar activeTab permission should also be checked manually.

Code quality and architecture

• pnpm lint runs ESLint's recommended checks plus unused-variable, equality, constant, and explicit-block rules.
• pnpm format formats source with Prettier; pnpm format:check verifies it without editing.
• pnpm check runs lint, formatting, unit tests, and the production build.
• The validation workflow checks Node 22/24, then runs the browser scenarios on Chromium. Actions are pinned to commit revisions and use read-only repository permissions.

The worker in background.js only registers extension events. scheduler.js owns serialized storage mutations and alarms through an injected browser adapter and clock. schedule.js contains recurrence arithmetic; date-engine.js combines date rules; rule-schema.js validates expressions; date-lists.js handles the offline holiday/workday database.

UI startup, runtime messaging, feedback, the schedule editor, and the recurrence dialog are separate modules. Shared limits live in limits.js. Runtime licenses are collected from the declared dependency graph rather than a package-manager-specific cache layout. Generated artifacts, license text, and private signing keys are excluded from formatting.

After an automatic or manual opening, the worker retains pending progress in memory and journals it in session storage until local storage accepts it. Session storage survives normal service-worker suspension; a recovery alarm retries persistence failures. Requests flush pending progress before reading state. A process crash between opening a tab and writing the journal, or a full browser restart while local storage is unavailable, can still replay an opening. This is not an exactly-once guarantee.

The extension has not been published to a browser store.