Encoding Corruption

Detects mojibake and replacement characters in visible text

Rule ID	content/mojibake
Category	Content
Scope	Per-page
Severity	warning
Weight	5/10

Solution

Mojibake means the bytes and the declared encoding disagree. Fix the declaration first: serve <meta charset="utf-8"> as the first thing in the head, and send Content-Type: text/html; charset=utf-8. If the declaration is already utf-8, the source itself was double-encoded, usually by a CMS migration that read utf-8 bytes as latin1 and re-encoded them. Re-import the affected content from the original source rather than search-and-replacing the visible symptoms, because the same corruption is usually present in fields you cannot see, such as meta descriptions and alt text.

What it checks

Three families of corruption, in visible text only:

Kind	Example	Meaning
utf8-as-latin1	It’s, café	utf-8 bytes decoded as latin1 or cp1252
replacement-char	caf�	the decoder gave up on those bytes
double-encoded-entity	visible  	the source said  

The check reads text with <script>, <style> and <noscript> excluded, never raw HTML, so an encoded sequence inside a script body is not reported. A page with no body is skipped rather than passed.

Severity depends on certainty. The replacement character is unambiguous corruption and fails. The other families warn.

Cause attribution

The finding cross-checks <meta charset> so the message names the actual fix rather than just reporting odd characters:

• No charset declared: the browser guessed. Add <meta charset="utf-8">.
• Charset is utf-8: the declaration is right, so the source is double-encoded. Re-import the content.
• Charset is something else: correct the declaration, then re-check whether the source is also double-encoded.

False positives

Correctly-decoded accented text is not corruption. Copy such as Un café à Paris, Grüße aus Köln, jalapeño, 25° or curly quotes stays clean, because the rule matches multi-character sequences that only arise from a bad decode, not individual accented letters.

Enable / Disable

Disable this rule

[rules]
disable = ["content/mojibake"]

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[rules]
disable = ["content/*"]

Enable only this rule

[rules]
enable = ["content/mojibake"]
disable = ["*"]