finder

finder /ˈfaɪndɚ/ noun
plural finders
finder
/ˈfaɪndɚ/
noun
plural finders
Britannica Dictionary definition of FINDER
[count]
: a person who finds something that was lost

finders keepers (losers weepers)

— used especially in children's speech to say that you can keep what you have found and do not need to give it back to the person who has lost it