NowUTC Reference
Overview
Browser-based UTC clock widget. No account, no tracking, localStorage only.
URL Parameters
| Param | Values | Description |
|---|---|---|
?tz= | Abbreviation or IANA name | Lock to a specific timezone (e.g. CST, America/Chicago) |
?until= | HH:MM or ISO datetime | Countdown timer to a UTC time (18:00) or date (2026-03-15T18:00Z) |
?view= | widget | desktop | Force a specific view mode (overrides auto-detection by viewport width) |
?embed=1 | 1 | Embed mode -- hides footer, settings gear, and widget link |
?shared=1 | 1 | Import shared config from URL. Combine with params below: |
&bg= | Hex (no #) | Background color (001F3F) |
&text= | Hex (no #) | Text color (7FDBFF) |
&favs= | Comma-separated IANA | Favorite timezones |
&fmt= | 12h | 24h | Secondary timezone time format |
&sec= | 0 | 1 | Show seconds on UTC clock |
&w= | 200-1200 | Widget popup width (px) |
&h= | 100-800 | Widget popup height (px) |
Keyboard Shortcuts
| Key | Action |
|---|---|
| ← → | Cycle through favorite timezones |
| C | Copy UTC timestamp (opens format tray) |
| E | Copy epoch (Unix seconds) |
| P | Open/close timestamp converter |
| ? | Toggle keyboard shortcut overlay |
| Esc | Close overlays (shortcut help, converter, format tray) |
Copy Formats
Click the UTC time to open the format tray. Click any row to copy.
| Format | Example |
|---|---|
| ISO 8601 | 2026-03-01T14:30:07Z |
| Unix (s) | 1772201407 |
| Unix (ms) | 1772201407000 |
| RFC 2822 | Sun, 01 Mar 2026 14:30:07 +0000 |
| SQL | 2026-03-01 14:30:07 |
| Human | March 1, 2026 at 2:30:07 PM UTC |
Timestamp Converter
Press P or click the paste icon next to the epoch display.
| Accepts | Example |
|---|---|
| Unix seconds (10 digits) | 1772201407 |
| Unix milliseconds (13 digits) | 1772201407000 |
| ISO 8601 | 2026-03-01T14:30:07Z |
| RFC 2822 | Sun, 01 Mar 2026 14:30:07 +0000 |
| Any Date.parse()-compatible string | March 1, 2026 |
Output includes all 6 copy formats plus local time and relative time.
localStorage Schema
{
"version": 3,
"defaultTz": "browser", // "browser" | "last"
"lastUsedTz": "", // IANA timezone string
"favorites": [], // IANA timezone strings
"colors": {
"bg": "#000000", // background hex
"text": "#FFFFFF" // text hex
},
"widgetSize": {
"width": 400, // popup width (px)
"height": 250 // popup height (px)
},
"timeFormat": "12h", // "12h" | "24h"
"showSeconds": false, // HH:MM vs HH:MM:SS
"wizardComplete": false, // first-time wizard completed
"tiles": [] // desktop tile defs [{ tz, label, color }]
}Key: nowutc_prefs
Desktop View
On viewports 900px and wider, NowUTC automatically switches to a tile grid showing UTC as a large primary tile plus one tile per favorite timezone. Use ?view=widget or ?view=desktop to override auto-detection. A toggle button in the bottom bar switches between views manually.
| Condition | View |
|---|---|
?embed=1 or popup window | Always widget |
?view=widget or ?view=desktop | URL override |
| Viewport >= 900px | Desktop (auto) |
| Viewport < 900px | Widget (auto) |
Embed Mode
Add ?embed=1 to hide all chrome. Generate a snippet from Settings > Embed.
<iframe src="https://nowutc.com/?embed=1" width="300" height="200" frameborder="0" title="NowUTC Clock"></iframe>
Settings Import/Export
| Action | Description |
|---|---|
| Export | Downloads nowutc-settings.json with full preferences |
| Import | Upload a JSON file to restore settings, then reloads |
| Reset | Clears localStorage and reloads with defaults |
PWA / Offline
Service worker uses network-first for HTML, cache-first for hashed assets. Install from your browser's address bar or menu for offline access and a native app feel.
Timezone Abbreviation Map
| Abbreviation | IANA Zone |
|---|---|
| UTC, GMT | UTC |
| EST, EDT | America/New_York |
| CST, CDT | America/Chicago |
| MST, MDT | America/Denver |
| PST, PDT | America/Los_Angeles |
| AKST, AKDT | America/Anchorage |
| HST | Pacific/Honolulu |
| BST | Europe/London |
| CET, CEST | Europe/Berlin |
| EET, EEST | Europe/Bucharest |
| IST | Asia/Kolkata |
| JST | Asia/Tokyo |
| KST | Asia/Seoul |
| AEST, AEDT | Australia/Sydney |
| NZST, NZDT | Pacific/Auckland |
About
Built by RJ Lindelof.
I kept googling "what is the UTC time" and bookmarking conversion pages. AWS dashboards were the worst -- some reports used my local timezone, others used the region's timezone (us-east-2), and some just said "UTC" with no context. I needed one small tool that stayed out of the way, showed UTC at a glance, and let me quickly convert between formats without hunting through tabs. So I built it.