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Social Media Text Formatter and Preview

A lightweight browser extension (Manifest V3) that lives in the side panel and helps you style social media posts with Unicode formatting — then preview how they’ll look before you publish.

It’s platform-neutral: LinkedIn, X (Twitter), Facebook, Instagram, and Threads are all supported. The output is plain Unicode text, so it pastes anywhere that accepts text.

Works in Chrome, Edge, and Firefox, and follows your OS/browser light or dark theme automatically.

Features

  • Inline editor — select part of your text (a headline, a quote) and apply a style to just that part, or apply a style to the whole post when nothing is selected.
  • Re-applyable styles — styles are normalized before each apply, so you can freely switch Bold → Italic → Script without stacking artifacts.
  • 14 text styles — Bold, Italic, Bold Italic, Sans, Bold Sans, Monospace, Underline, Strikethrough, Script, Fraktur, Double-struck, Fullwidth, UPPERCASE, lowercase.
  • List tools — bullet, numbered, checklist, and dash lists applied to whole lines.
  • Emoji picker — categorized emojis inserted at the cursor.
  • Live preview — a mock post card per platform with author, avatar, and realistic “see more / see less” truncation.
  • Character counter — per-platform limit (e.g. 280 for X, 3,000 for LinkedIn) that turns red when exceeded.
  • One-click copy — copies the raw formatted text to your clipboard.

How it works

Formatting uses Unicode character blocks (Mathematical Alphanumeric Symbols, Letterlike Symbols, etc.), so “bold” text is actually distinct Unicode glyphs — not markup. That’s why it survives a copy-paste into any platform. Underline and strikethrough use combining marks.

Installation

The extension isn’t published on the Chrome Web Store, Edge Add-ons, or AMO yet, so for now install it manually using one of the methods below. Grab the latest zips from the Releases page, or build them yourself from source.

Chrome / Edge

Option A — from a release zip

  1. Download social-media-text-formatter-chrome.zip from the latest release.
  2. Unzip it to a folder (Chrome/Edge cannot load a zip directly).
  3. Open chrome://extensions (or edge://extensions).
  4. Enable Developer mode (top-right toggle).
  5. Click Load unpacked and select the unzipped folder.
  6. Pin the extension, then click its toolbar icon to open the side panel.

Option B — from source (Developer mode)

  1. Clone or download this repository.
  2. Open chrome://extensions (or edge://extensions).
  3. Enable Developer mode (top-right toggle).
  4. Click Load unpacked and select the repository folder (it already contains manifest.json).
  5. Pin the extension, then click its toolbar icon to open the side panel.

Either way, the extension stays installed until you remove it — “unpacked” only means it wasn’t installed from a store, not that it’s temporary.

Firefox

Firefox only runs signed extensions permanently. Loading it yourself (from source or from the zip) installs it as a temporary add-on that’s removed when Firefox restarts — that’s expected for local testing, not a bug.

Option A — from a release zip

  1. Download social-media-text-formatter-firefox.zip from the latest release.
  2. Unzip it to a folder.
  3. Open about:debugging#/runtime/this-firefox.
  4. Click Load Temporary Add-on and select the manifest.json inside the unzipped folder.
  5. Click the toolbar icon to open the sidebar.

Option B — from source (build the Firefox manifest yourself)

  1. Clone or download this repository.
  2. Run ./scripts/package.ps1 to build dist/firefox/ (this swaps in manifest.firefox.json as manifest.json), or manually copy manifest.firefox.json over manifest.json in a copy of the folder.
  3. Open about:debugging#/runtime/this-firefox.
  4. Click Load Temporary Add-on and select the manifest.json in dist/firefox/.
  5. Click the toolbar icon to open the sidebar (Firefox uses sidebar_action instead of Chrome’s side_panel API).

For a permanent Firefox install without repeating this after every restart, the add-on needs to be signed — either by submitting it to addons.mozilla.org or through Mozilla’s unlisted signing process.

Usage

  1. Type or paste your post into the editor.
  2. Select text and tap a style — or apply a style to everything with no selection.
  3. Add lists, emojis, and pick a platform to preview.
  4. Click Copy and paste into your social platform.

Privacy & security

  • No network access. The extension makes no external requests and loads no remote resources.
  • Minimal permissions. It requests only sidePanel (Chrome/Edge) or sidebar_action (Firefox) — no host permissions, tabs, or content scripts.
  • No data collection. Your text never leaves the browser; nothing is stored or transmitted.
  • Clipboard is write-only — the extension never reads your clipboard.
  • Full policy: Privacy Policy.

License

Licensed under the Apache License 2.0 — see LICENSE and NOTICE.

You’re welcome to fork and build on this project. In return:

  • Keep attribution. Retain the copyright and NOTICE, and credit the original project (“Social Media Text Formatter and Preview” by bingkil).
  • Use your own branding. The bingkil name and the logo/icon files are trademarks and are not covered by the license — replace them with your own before redistributing.

View the source on GitHub →