What is a validator?

Imagine a shared ledger of transactions that isn’t kept by one bank but by many computers. Who checks whether the next page is correct? On Proof of Stake networks, that job falls to validators, following the network’s rules.

Their software checks, among other things, the digital signatures and whether the transactions are allowed based on the available balances. Depending on the protocol, one validator is selected to propose the next block and others attest that it’s valid. Their attestations help the network agree on its history. No validator decides alone which transactions are considered final.

To take part, crypto is locked up through staking, either by the operator themselves or, where allowed, by users who delegate their stake to them. A validator can earn rewards for operating correctly. Hardware requirements, the required stake and the selection method vary by blockchain. Also, a full node can verify the blockchain without taking part in consensus as a validator.

Why it matters

When you send crypto, you rely on the network’s consensus mechanism to confirm your transaction. Validators are part of this mechanism on Proof of Stake networks. Their availability and how power is spread among independent operators affect the network’s security and resilience.

We think the number of validators isn’t enough to judge decentralization. If many of them are controlled by the same company or depend on shared infrastructure, real independence may be lower than their number suggests.

What to watch out for

If you stake through a validator, rewards aren’t guaranteed. The operator’s commission, downtime and the withdrawal rules all affect the outcome. On some networks, specific violations can lead to a cut in the staked funds (slashing). Simply going offline isn’t treated everywhere the same way as a conflicting signature. Also check whether you’re only delegating your stake or also handing custody of your crypto to a third party: they are not the same thing.