蔡 is a Chinese hanzi, listed here under the keyword “surname”. It is built from 艹 (grass) and 祭 (sacrifice to). It appears as a component in 3 other characters in this index.
On KumiJi Glyph Explorer, open the parts search and type “grass” + “sacrifice to”. 蔡 is among the results, together with every other character containing the same shapes.
Open 蔡 in the interactive kanji search
to expand every part down to its smallest pieces, add your own names and mnemonic stories,
or search for other characters by their parts.