FAQ

Can it replace bad words with ****?

Yes. Use censor, or check(text).censor() if you also want to know what matched:

censor('you muji');             // 'you ****'
check('you muji').censor();     // 'you ****'

See Censoring.

Can I highlight matches instead of hiding them?

Yes. Use the positions from findProfanityMatches to build a TextSpan. See Highlight matches.

Can I add my own words?

Yes. Pass extraWords to flag more words, and allowWords to never flag a word, such as a name on your site:

final filter = ProfanityFilter(extraWords: ['someword'], allowWords: ['somename']);

filter.containsProfanity('s0mew0rd');   // true

Extra words are matched like the built-in ones, so leetspeak, stretched letters and postpositions are still caught. To add words for everyone, see Contributing.

Why was this word flagged?

Run the text through findProfanity to see which word matched, and tokenize to see the words the filter checked:

findProfanity('damn it', strictness: Strictness.strict);   // ['damn']
tokenize('damn it');                                       // ['damn', 'it']

If an ordinary word or a name is flagged at the standard or lenient level, please report it.

Why wasn't this word caught?

It's probably not in the word lists, or it's in a stricter level than the one you use. Check the lexicon:

lexicon.words.firstWhere((e) => e.text == 'idiot');
// LexiconEntry(idiot, english, standard)

If it isn't there, suggest it.

Which strictness should I use?

Use the default, Strictness.standard, for most apps. Use Strictness.lenient if mild insults are fine in your community. Use Strictness.strict only when a person reviews what gets flagged, because it catches a few ordinary words, like damn. See Block severe words, review the rest.

Is checking in the app enough?

No. Anyone can call your API directly, so check again on your server before saving anything. Checking in the app is still useful for warning people as they type. Every port gives the same results, so your server can be in JavaScript, Python, Go, PHP or Dart.

Is it fast?

Yes, for typical user text like comments, reviews and names. A filter builds its lookup tables once, and each check is a single pass over the words in the text. It's fast enough to run on every keystroke. To both check and censor, use check(text), which reuses one scan for both.

Does it give the same results as the JavaScript package?

Yes. Every port uses the same word lists and matching rules, and is tested against the JavaScript package's output. Dart strings are UTF-16, like JavaScript's, so even the match positions are the same.