dtlTraders is kinda similar to shopkeepers in that you create shopkeepers/traders, but in shopkeepers, you can only have the default amount of trades on one shopkeeper, and you cant change that default. With dtlTraders you turn an NPC into a trader with a trait instead of just having a villager or mob like in shopkeepers. It just seems like a better plugin that would help people with servers that have a lot of trades. Like my server, I have to have a bunch of villagers just to exchange all the different ores (and amounts of ores) into gold or money, with this plugin you can put it all into one trader.
forgot to add the link
https://www.spigotmc.org/resources/dtltraders.35890/
Um you do know that you can actually change the amount of items in shopkeepers, you can change that in configuration.
last time i checked the page for it said it was unsupported and that it wasnt a feature unless you coded it your self