Mod offer full rewrite of Minecraft trading system.

Player now buy and sell items using abstract currency.
Everything what could be bought from villages can be sold to any villager (excluding loafers) for 1/24 of a price.
Career level of villagers depends only from their own wealth. Wealth is raised whenever player buy items (excluding emeralds) from them.
Single GUI screen show all trades, including unavailable due to insufficient villager career level.
Emeralds have a fixed selling and buying price of 144 Minecraft coins.
Villagers trades added by custom mods are supported.

You can add your own trades. To do so download following file:

http://www.mediafire.com/file/72cvgl4v6e3l4cx/freetrading_custom_trades.json

And drop it in `.minecraft/config` directory. After that you can edit it to add more items to sell and buy. All keys in JSON are optional.

If player inventory can't hold offered items, deal will be canceled and related chat message will appear at both sides of a deal.
If one of a players press "Seal a deal" while other not, GUI will show a lock for him and his partner. After "Seal a deal" is pressed player, who pressed that button, cannot alter offered items and money.
Trade can be initiated only if player, who initiate trade, has no item in his main hand.

If Forge Essentials (https://minecraft.curseforge.com/projects/forge-essentials-74735) mod installed on a server, Freetrading will use a wallet provided by Forge Essentials.

James Velasquez (xyberviri) - had add EnderPay support.