堅 is a traditional Chinese hanzi, listed here under the keyword “hard”. It is built from 臤 (hard) and 土 (soil). It appears as a component in 6 other characters in this index.
On KumiJi Glyph Explorer, open the parts search and type “hard” + “soil”. 堅 is among the results, together with every other character containing the same shapes.
Open 堅 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.