MD010 - Use spaces instead of tabs¶

Aliases: no-hard-tabs

What this rule does¶

Replaces tab characters with spaces to ensure consistent indentation across all editors and platforms.

Why this matters¶

• Consistency: Tabs display differently in different editors (2, 4, or 8 spaces wide)
• Team collaboration: Mixed tabs and spaces create confusing indentation and merge conflicts
• Tool compatibility: Many Markdown tools and platforms expect spaces for proper formatting
• Readability: Consistent spacing makes documents easier to read and maintain

Examples¶

✅ Correct¶

* Shopping list
    * Fruits
        * Apples
        * Bananas
    * Vegetables
        * Carrots
        * Broccoli

    Remember to check for freshness!

❌ Incorrect¶

→ represents a hard tab character.

* Shopping list
→* Fruits
→→* Apples
→→* Bananas
→* Vegetables
→→* Carrots
→→* Broccoli

→Remember to check for freshness!

🔧 Fixed¶

* Shopping list
    * Fruits
        * Apples
        * Bananas
    * Vegetables
        * Carrots
        * Broccoli

    Remember to check for freshness!

Configuration¶

[MD010]
spaces-per-tab = 4    # Number of spaces to replace each tab with (default: 4)
code-blocks = false   # Skip tabs inside code blocks (default: false)

Configuration options explained¶

• spaces-per-tab: How many spaces to use when replacing each tab character.
• code-blocks: When false (default), hard tabs inside fenced and indented code blocks are skipped - tabs are often required there (Makefiles, Go) and rewriting them would corrupt examples. Set to true for markdownlint-parity behavior that flags tabs everywhere, including code blocks.

Behavior change: Earlier versions skipped tabs in fenced code blocks while still flagging indented ones. MD010 now treats both code-block types consistently and, by default, does not flag tabs in either. Note that a document whose content starts with a tab-indented line is a CommonMark indented code block, so leading tabs there are no longer flagged by default. Set code-blocks = true to flag tabs in all code blocks.

Automatic fixes¶

This rule automatically replaces each tab character with the configured number of spaces (default: 4). This ensures your document looks the same in every editor.

Learn more¶

• CommonMark specification - Technical details about tab handling

Related rules¶

• MD009 - Remove trailing spaces
• MD007 - Keep list indentation consistent
• MD005 - Keep list indentation consistent