Making gold, and the Exchange

Gold buys potion upgrades, refines and polish for your gear, companions, your Fortress and the Moth Coach. Here is where it comes from.

Where gold comes from

Fighting. Every kill drops a little gold, and drops sell to any shop.
The Exchange. Usually the best money: other cats pay more than shops do. More below.
Swiping, knocking things off the Tall Ones' tables. Less than fighting, but steady, and it makes Lucky Charms to sell.
The Bounty Board in every town: three bounties a day for gold and Bounty Marks.
Contests. Each week features one life skill, and the three cats who gain the most XP in it win millions of gold.

The Scratching Post Exchange

Every town has an Exchange stall. You can look from anywhere; posting, buying and collecting need a town.

Stackable things (materials, meals, kits, Bottled Dreams, boxed wardrobe looks) trade through buy and sell offers, like a market. A new offer trades at once with the best waiting offers at their price, and otherwise waits for a match.
Gear is one of a kind, so it is listed at a fixed price, and buyers browse by slot, rarity and level.
You have 8 offer slots. Your gold or goods are held while an offer waits, and offers keep filling while you nap.
The seller pays a 2% tax on each sale. It leaves the game, which keeps prices honest.

What other cats will pay for

Gathered materials. Crafting, brewing, cooking and the Fortress all eat them, and not everyone wants to gather. See the materials.
Meals and kits. Every fighting cat wants a meal, and Grooming Balms, Scout's Maps and Lucky Charms only come from support skills.
Crafted gear with a good rarity roll. Shops pay little for crafted pieces, so sell them to cats.
Wardrobe looks. They drop boxed and rarely, and cats love to dress up. See the wardrobe.
Notable fish, and festival currency while a festival runs.

Spending it well

Early on, potion upgrades and gear upgrades matter most. Refining gear at the Clawsmith raises its rarity; from mythic, Polish adds a little more each time for as long as you can pay. Training companions and building the Fortress pay off over the long run.