YaCy (mai suna "ya see") injin bincike ne da aka rarraba kyauta, wanda aka gina akan ka'idodin cibiyoyin sadarwa na peer-to-peer (P2P). Jigon sa shine tsarin kwamfuta da aka rubuta a cikin Java wanda aka rarraba akan kwamfutoci da yawa, tun daga watan Satumbar 2006, wanda ake kira YaCy-peers. Kowane YaCy-peer da kansa yana rarrafe ta Intanet, bincike da fihirisa sun sami shafukan yanar gizo, kuma suna adana sakamakon ƙididdiga a cikin bayanan gama gari (wanda ake kira index) wanda aka raba tare da sauran abokan YaCy ta amfani da ka'idodin hanyoyin sadarwar P2P. Injin bincike ne na kyauta wanda kowa zai iya amfani da shi don gina hanyar bincike don intranet ɗin su kuma don taimakawa bincika intanet ɗin jama'a a sarari.