Highlight Non-ASCII

An Obsidian plugin that highlights any character outside the standard ASCII range (0x00-0x7F) in both Edit Mode (Live Preview) and Reading View.

Useful for catching invisible Unicode characters, accidental special characters, or non-standard punctuation in your notes.

Features

• Highlights non-ASCII characters with a visible red background

• Works in Edit Mode (Live Preview) with optional Reading View support

• Auto-replace -- batch replace common non-ASCII characters with ASCII equivalents via the command palette

• Configurable replacement rules with a find/replace list in settings

• Configurable allowlist to exclude specific characters (accented letters, emojis, etc.)

• Per-note control via frontmatter

• Status bar counter -- shows the number of non-ASCII characters in the current note alongside Obsidian's word and character counts

• Reading view toggle -- optionally enable highlighting in preview/reading mode (off by default)

• Customizable highlight CSS

• Toggle on/off from settings or the command palette

  

Usage

1. Install and enable the plugin.

2. Non-ASCII characters will be highlighted automatically.

3. Use Settings > Highlight Non-ASCII to configure:

   • Enable highlighting -- toggle the feature on or off
   • Highlight in reading view -- enable highlighting in preview/reading mode (off by default, since edit mode is usually sufficient)
   • Allowed characters -- paste characters that should NOT be highlighted (e.g. accented letters, specific emojis)
   • Custom CSS -- edit the highlight style directly

4. Use the command palette: Toggle non-ASCII highlighting to quickly enable/disable.

   

Auto-replace

The plugin includes a batch replacement feature for cleaning up common non-ASCII characters like curly quotes, em dashes, and non-breaking spaces.

How to use

1. Open a note that contains non-ASCII characters
2. Open the command palette (Ctrl/Cmd + P)
3. Run Highlight Non-ASCII: Auto replace non-ASCII characters
4. All matching characters in the note will be replaced according to your configured rules

Default replacement rules

The plugin comes with these defaults out of the box:

Find	Replace	Description
' (U+2018)	'	Left single curly quote
' (U+2019)	'	Right single curly quote
" (U+201C)	"	Left double curly quote
" (U+201D)	"	Right double curly quote
-- (U+2013)	-	En dash
--- (U+2014)	--	Em dash
... (U+2026)	...	Horizontal ellipsis
(U+00A0)		Non-breaking space

Customizing rules

You can add, edit, or remove replacement rules in Settings > Highlight Non-ASCII under the Auto-replace rules section. Each rule shows:

• Find -- the character to search for
• Replace -- the text to replace it with
• Unicode codepoint -- the U+ identifier for the find character
• Remove button to delete the rule

Click Add rule to create a new find/replace pair.

Disabling for specific notes

Add the following frontmatter to any note where you want to turn off highlighting:

---
highlight-non-ascii: false
---

If the property is missing or set to true, highlighting remains active (as long as the global toggle is enabled).

Installation

Obsidian Community Plugin (pending)

This plugin has been submitted for review to the Obsidian community plugin directory. Once approved, you will be able to install it directly from Settings > Community plugins > Browse by searching for "Highlight Non-ASCII".

Using BRAT

You can install this plugin right now using the BRAT plugin:

1. Install BRAT from Settings > Community plugins > Browse (search for "BRAT" by TfTHacker)

2. Open the BRAT settings

3. Under the Beta plugins section, click Add beta plugin

   

4. In the overlay, enter this plugin's repository: https://github.com/saltyfireball/obsidian-highlight-non-ascii (or just saltyfireball/obsidian-highlight-non-ascii)

   

5. Leave the version set to latest

   

6. Click Add plugin

Manual

1. Download the latest release from the Releases page
2. Copy main.js, manifest.json, and styles.css into your vault's .obsidian/plugins/highlight-non-ascii/ directory
3. Enable the plugin in Settings > Community plugins

License

MIT -- see LICENSE for details.