Forbidden Word Checker

When to use?

Use it to test forbidden-word filter logic when building a community service or chatbot, or to check whether a post contains certain words before publishing.

How to use

• Enter the forbidden-word list, one per line.
• Enter the text to check.
• Found words and their positions are highlighted.

Input Explanation

Enter the forbidden-word list (one per line) and the source text to check.

Calculation Basis

It searches each word from the list, collects start/end positions in the text, and highlights matches. With case-insensitive on, only the comparison string is lowercased.

Usage Examples

• Test a word filter - Check whether a service's forbidden-word list is detected correctly.
• Pre-review posts - Quickly check whether text contains banned words before publishing.
• Pre-check comments - Check whether a comment contains banned expressions before posting.

Examples

• Add a word to the list → it is highlighted wherever it appears in the text
• Register several words → all matched words in a post are highlighted

Cautions

• The word list and results are processed only in the browser and not sent to a server.
• Counts can vary by how spaces and line breaks are handled.

Guides

Catching spaced or dotted evasions

People often insert dots or spaces between letters (e.g. "b.a.d") to slip past filters. Building a pattern that tolerates noise characters between letters lets the checker catch these variants too.

Avoiding over-filtering

Blocking a syllable or fragment that also appears in normal words will mask harmless sentences. Keep the forbidden list built around precise whole words rather than broad fragments.

FAQ

Is it case-sensitive?

Choose the case-insensitive option to check regardless of case.

Is the word data stored?

No. All processing happens only in the browser.

How do I enter the word list?

Enter your reference words and the tool finds and marks them in the text.

Are partial matches caught?

A forbidden word is detected if it appears as a substring of the text.

Related Tools

• Text Highlighter - Highlight multiple keywords in text and see found keywords and match counts in real time.
• Text Masking Tool - Mask parts of personal data such as emails, phone numbers, and names with *.
• Line Filter - Filter lines of text by keyword include/exclude conditions.
• Character Counter - Count characters with and without spaces, and line count, in real time.
• Byte Counter - Calculate the byte length of text when stored as UTF-8.
• Case Converter - Convert text, variable names, and filenames to UPPER, camelCase, snake_case, kebab-case, and more.