How I Built a Privacy-First Word Counter Chrome Extension (with CJK Support)

I’ve always been frustrated with online word counters.

You copy text, paste it into a random website, and hope it doesn’t store your content or track you. For writers, editors, and students who work with sensitive drafts, that’s a real problem.

So I built Instant Word Counter — a Chrome extension that counts words, characters, and reading time instantly, offline, and 100% locally. No text ever leaves your device.

Why another word counter?

Most existing extensions either:

• require copy-pasting,


• use clunky right-click menus,


• or send your text to external servers for processing.

I wanted something faster and truly private.

How it works

1. Select any text on a webpage.


2. Click the extension icon (or press Alt+W).


3. See word count, character count (with/without spaces), and estimated reading time in a clean popup.

If no text is selected, the extension gently guides you. No clutter, no confusion.

CJK character counting

One feature I’m especially proud of: the extension correctly handles Chinese, Japanese, and Korean (CJK) characters. When CJK characters are detected, it automatically switches from "Words" to "CJK Characters" — something most word counters get completely wrong.

It uses the Intl.Segmenter API for word segmentation and falls back to a regex-based counter for older browsers.

Tech stack

• Vanilla JavaScript (no frameworks)


• Chrome Manifest V3


• Intl.Segmenter for accurate word counting


• chrome.i18n for localization (10 languages so far)


• All processing happens locally — no backend, no analytics, no tracking

Privacy by design

• No data collection


• No network requests


• No cookies


• The extension only requests activeTab and scripting permissions — nothing else

What I learned

• Intl.Segmenter is powerful but still limited for mixed-language texts


• Chrome Web Store localization is surprisingly tricky (detailed descriptions must be added manually per language)


• Users genuinely care about privacy — several early reviews mentioned it as the main reason for installing

Try it out

Instant Word Counter is free and available on the