Pluralizer: Singular and Plural English Nouns

A free pluralizer that converts English nouns between singular and plural and gets the hard cases right. Most words just take an -s, but real English is messier: words ending in s, x, z, ch or sh take -es (box → boxes), a consonant plus y flips to -ies (city → cities), and many -f or -fe words switch to -ves (leaf → leaves, knife → knives). On top of the suffix rules it carries a table of more than forty irregular plurals (child → children, man → men, foot → feet, mouse → mice, person → people) and the Latin and Greek loanwords that trip people up (datum → data, cactus → cacti, analysis → analyses). Zero-plural nouns such as sheep, fish, deer and series, plus true uncountables like information and equipment, are left unchanged. The converter works both ways, so you can singularize a plural just as easily, and it keeps your capitalization so Child becomes Children and BOX becomes BOXES. Paste one word per line to convert a whole list at once, then copy the result with a single click. Everything runs locally in your browser.