What is validator commission on Solana?
Commission is the share of your staking rewards that a validator keeps as its fee. On Solana there can be two: the inflation commission, a cut of the new SOL the network pays out every epoch (about a day), and the MEV commission, a cut of MEV tips (extra income from ordering transactions). You receive what's left after both.
A stable fee tells you more than the lowest one
Commission comes straight out of your rewards. Say your stake earns 1 SOL in inflation rewards: at 5% commission the validator keeps 0.05 SOL and you get 0.95.
Lower isn't automatically better. A 0% commission can be a way to attract stake before a raise later, and any change applies to every delegator at once. A record of stable fees tells you more than the lowest number on a list.
At 100%, the validator keeps all inflation rewards and its delegators get none of them, the main part of staking income. Even then, your SOL stays yours: commission affects rewards, never the coins you staked.
See both commissions, and a red flag for any raise
The fees card on each validator page, and the Fees column in the list, show both commissions as "rewards / MEV", for example 0% / 5%. Red flags mark a validator that raised its fees recently (Fees raised) or keeps 100% of inflation rewards (Keeps 100%, Score 0). Our Telegram alerts tell you if your validator changes its commission.
Questions
Look for a number that is low and has stayed the same over time. A validator that has held 5% for two years tells you more than one at 0% with a month of history. Fees count for 35 of the 100 points in our Score.