New Tab (countdown)

A dead-simple Chrome new-tab page: one logo, one big number counting down to your deadline in fractional days, and a row of links. Modeled on the YC startup dashboard ("14.391769 days") that a founder pinned to their browser.

What it shows

• A small logo (a letter in an accent square, an emoji, or your own image) with an optional subtitle underneath.
• One big number: days left until your featured deadline, with the fractional part ticking live beside it (89.100286 days).
• Smaller secondary deadlines below it (click one to make it the big number).
• A row of quick links (Calendar | Mail | GitHub | Docs), pipe-separated.

That's the whole page. Calm, centered. The countdown runs fully offline (no accounts, no servers, no tracking). Favicons and image-URL logos are the only things that touch the network, and only if you use them.

Optional extra (off by default): a faint "alive" age line below the links.

The extension is named "New Tab" on purpose, so Chrome's little attribution chip at the bottom of the page blends in. Rename it in manifest.json if you like.

Install (load unpacked, ~30 seconds)

This is the standard way to run a Chrome extension you have the files for. It does not require the Chrome Web Store.

1. Open Chrome and go to chrome://extensions
2. Turn on Developer mode (top-right toggle)
3. Click Load unpacked
4. Select this folder: deadline-tab
5. Open a new tab.

To update later, edit the files and click the refresh icon on the extension card.

Chrome only lets one extension own the new tab page at a time. If you already have a new-tab extension, disable it first.

Chrome Web Store

Publishing to the store needs your own Google developer account (a one-time $5 fee) and a short Google review. The packaged deadline-os.zip is ready to upload at https://chrome.google.com/webstore/devconsole if you want to list it. Load unpacked above is instant and free for personal use.

Customize

Click ✎ Customize in the top-right corner of the new tab.

• Deadlines: name, an optional subtitle (shows under the logo), a date (date only, your local timezone), which one is featured (the big number), and a logo. Click the icon button to open a picker: choose an emoji from the grid, upload an image (auto-shrunk, so size does not matter), or paste an image URL. Add or delete as many deadlines as you want.
• Quick links: label + URL, shown with the site's favicon in the editor. URLs without a scheme get https://; unsafe schemes are blocked.
• Look: background (Paper / Ink / Slate / Sage / Sand / Midnight / Match system) shown as color swatches, font (Sans / Rounded / Serif / Mono) shown as live previews, and how many fraction digits to show (3 / 6 / 9).
• Age line (optional): a faint "alive" readout, with a date-of-birth field.

Everything saves automatically.

Files

manifest.json        MV3 manifest, overrides the new tab page
newtab.html          the page
newtab.css           styling (CSS variables per theme)
src/theme-init.js    applies the saved background before first paint (no flash)
src/time.js          pure date math (fractional-days countdown, age, formatting)
src/store.js         persistence (chrome.storage.local + localStorage fallback)
src/app.js           the rAF render loop and the settings panel
icons/               extension icons
src/time.test.mjs    unit tests (run: node src/time.test.mjs)
make_icons.py        regenerates the icons (run: python3 make_icons.py)

Tech notes

• Manifest V3, vanilla JS, no build step, no dependencies.
• One requestAnimationFrame loop with write-on-diff: only the fractional digits that actually change touch the DOM each frame.
• tabular-nums so the number never jitters as it ticks.
• Honors prefers-reduced-motion (freezes the fractional digits).
• All scripts are external files (MV3 forbids inline scripts in extension pages).
• Link URLs are restricted to safe schemes; uploaded logos are validated.