COPAC is a union catalogue. It provides free access to the merged online catalogues of 24 of the largest university research libraries in the UK and Ireland, plus the British Library, the National Library of Scotland, and the National Library of Wales/Llyfrgell Genedlaethol Cymru.
COPAC is a MIMAS service, produced at Manchester Computing, University of Manchester. COPAC is funded by JISC.
There are three main interfaces to COPAC. The Web interface (the Web/Z39.50 gateway) is the one used most. However, you can also access COPAC using the Text Interface (telnet) or via the Z39.50 Target.