Probably Xavier could make a database search for that. But, it is very hard to measure catalogue contribution, even if we narrow it down to coin editing (excluding some important tasks as Outings, Numisdocs, Forum moderation, MPCC and of course, Xavier's work on the server itself).
When we take coin editing, lot of work can be done through translation menu, and that is never counted anywhere. And even with plain count of coins added, there are problems. It is much easier to add modern coin compared to making research and work on medieval or ancient coin.
But, in order to at least a bit satisfy your question, many of most contributing members usually became team members, so they are here:
https://en.numista.com/team.php
There are some notable ones as far as I know:
- Former master referee KennyG who holds record of 7446 coins added .
- Cyrrillius, who obviously aims to broke that record - 6289 coins added
- Apuking, who is only a step behind with 6116 coins added
There there is a great gap until "3000" group, which includes AmerSalmeh, Stavros and me

, then I am losing count.
Also, there is new holder of "coins edited" record, which will probably stand unbeaten by man.
https://en.numista.com/echanges/profil.php?id=110280