KAR is the default fee token on Karura.
KSM is now enabled also as a fee token on Karura.
The default fee token on Karura is KAR. The system will automatically find the next available and supported fee token if the default token has zero balance. The default order is as follows
You can check this on-chain
Chain state >
For example, if a user has no KAR balance and no kUSD balance, but some KSM balance, then the system will automatically use KSM as fee token.
Users can set their next default fee token to tokens other than kUSD e.g. KSM by executing the following transaction:
You do NOT need KAR in the balance to perform any transactions on Karura. If you hold only KSM (or other supported fee tokens) on the Karura network, you can still trade KSM on Karura Swap and mint kUSD without holding KAR.
This is what happens behind the scene if you trade KSM on Karura Swap without KAR in balance
User has a brand new account, with some KSM just cross-chain transferred KSM from the Kusama network
User trades 0.03 KSM for KAR on Karura App, it is seamless without extra user action
This is an example transaction illustrated the above process. There are two
0.003739782821 KSM for
0.103651490206 KAR , where
0.1 KAR was the Existential Deposit amount, and
0.003651490206 KAR was the transaction fee.
This is the actual Swap event.