A Chrome extension for the timestamps I kept pasting into a search bar

Pipeline logs, API responses and database rows are full of epoch timestamps. Every time, the routine was the same: copy the number, open a tab, search “epoch converter”, paste, read, close. A few seconds each, many times a day — exactly the kind of friction that’s worth automating away.

1. 1
   A page with an input box. The first draft was a plain HTML page: paste a value, see the date. It worked, but it was still a separate tab.
2. 2
   Selection instead of typing. Next, it read whatever text was selected on the page — removing the copy-paste step entirely.
3. 3
   A Chrome extension. Packaged as a content script, so it works on every site without opening anything.
4. 4
   A tooltip instead of an alert. The first version popped a blocking alert; the current one draws a small tooltip next to the cursor and removes it after three seconds.

The manifest injects a content script into every URL with only the activeTab permission. The script listens for mouseup; if Ctrl is held and the selection is at least ten characters and parses as a number, it converts it and shows the result at the cursor.

document.addEventListener("mouseup", (event) => {
  if (!event.ctrlKey) return;
  const selection = window.getSelection().toString().trim();
  if (selection.length < 10) return;

  const epoch = parseInt(selection, 10);
  if (isNaN(epoch)) return;

  const utc = new Date(epoch * 1000).toISOString();
  showInfoTooltip(`UTC: ${utc}`, event.pageX, event.pageY);
});

It also shows UTC only. I wrote a helper for my own time zone but never wired it into the tooltip, and reading logs from another region is exactly when you need both.

1. 1
   Detect milliseconds by length (13 digits) and say which unit it assumed.
2. 2
   Show UTC and local time side by side, with the offset.
3. 3
   Move to Manifest V3 and add a right-click menu entry, so it doesn’t depend on a key held during selection.