FUNDAMENTALS OF CRYPTO

What Is a Validator in Crypto?

Every blockchain network needs a mechanism for agreeing on the truth: which transactions are valid, which blocks are legitimate, and what the correct state of the ledger is at any given moment. This agreement process is called consensus, and the participants who make it work are called validators.

In proof-of-stake blockchain networks, validators are the entities responsible for proposing new blocks, attesting to their validity, and maintaining the integrity of the network. They have replaced miners as the primary security mechanism in networks like Ethereum, and understanding what they do, how they’re incentivised, and what risks they carry is foundational knowledge for anyone invested in proof-of-stake assets or considering staking.

The Problem Validators Solve

To understand validators, it helps to understand the problem they solve.

A blockchain is a distributed ledger: thousands of computers around the world each hold a copy of the same transaction history. For the ledger to be useful, all of these copies must agree. But in a decentralised network with no central authority, how does agreement happen when participants don’t know or trust each other?

This is the blockchain consensus problem, and it is the fundamental challenge that every blockchain design must solve. Bitcoin solved it through proof-of-work: miners compete to solve computationally intensive puzzles, with the winner earning the right to add the next block. The cost of the computation makes attacking the network expensive. Honest participation is more profitable than dishonest participation.

Proof-of-stake solves the same problem differently. Instead of requiring computational work, it requires participants to stake, or lock up, a defined amount of the network’s native cryptocurrency as collateral. This staked capital is the security deposit. If a validator behaves dishonestly or incorrectly, a portion of their staked capital is destroyed. This economic penalty, called slashing, makes attacking the network expensive without requiring the massive energy consumption of proof-of-work mining.

Validators are the participants who stake capital and perform the consensus work in proof-of-stake networks.

What Validators Actually Do

The work of a validator involves several specific functions that collectively maintain the blockchain’s security and continuity.

Block proposal. Validators are periodically selected to propose new blocks. On Ethereum, one validator is selected per slot (every 12 seconds) to propose the next block. The selection is pseudorandom but weighted by the amount of ETH staked: validators with more stake have a proportionally higher chance of being selected to propose a block.

Attestation. The majority of validators’ work is attestation rather than block proposal. In each slot, validators that are not proposing a block are assigned to attest to the validity of the proposed block. They check that the proposed block follows the network’s rules, contains valid transactions, and builds correctly on the previous block. Valid attestations are included in subsequent blocks and earn rewards. Attestations that contradict the honest majority are penalised.

Finalisation. Ethereum’s proof-of-stake consensus uses a mechanism called Casper FFG to achieve finality: a state where a block is cryptographically guaranteed to be part of the canonical chain and cannot be reversed without destroying at least one-third of all staked ETH. This is different from Bitcoin’s probabilistic finality, where blocks become progressively harder to reverse as more blocks are added on top.

Sync committee participation. A rotating subset of validators participate in sync committees that produce compact signatures of the current chain head, enabling light clients to verify the chain state without downloading the full blockchain. Sync committee selection is random and participation earns additional rewards.

Validators vs Miners: The Key Differences

Before Ethereum’s transition to proof-of-stake in September 2022, known as The Merge, Ethereum used proof-of-work mining. The shift to validators represents a fundamental change in how the network achieves security and consensus. Understanding the differences clarifies why the industry has broadly moved toward proof-of-stake.

Security mechanism. Miners secure the network through the economic cost of electricity and hardware. Attacking a proof-of-work network requires acquiring more than 50% of its hash rate, an enormous physical and financial undertaking. Validators secure the network through staked capital. Attacking a proof-of-stake network requires acquiring more than one-third of all staked assets, also an enormous financial undertaking, and a successful attack destroys the attacker’s staked capital through slashing.

Energy consumption. Proof-of-work mining consumes enormous amounts of electricity by design: the energy expenditure is the source of the security. Proof-of-stake validation consumes a tiny fraction of this energy because it does not require competitive computation. Ethereum’s transition to proof-of-stake reduced its energy consumption by approximately 99.95%.

Barriers to participation. Running a Bitcoin mining operation competitively requires specialised hardware (ASICs), significant capital, access to cheap electricity, and technical infrastructure. Running an Ethereum validator requires 32 ETH, a standard computer, a reliable internet connection, and basic technical knowledge to maintain uptime. The validator model is more accessible than competitive mining.

Capital requirements. Bitcoin mining requires capital investment in hardware that depreciates and becomes obsolete as more efficient hardware is released. Ethereum validation requires capital investment in ETH that remains liquid and earns yield rather than depreciating as hardware does.

Ethereum Validators: The Specifics

Ethereum is the largest proof-of-stake network by market capitalisation and the primary reference for understanding how validators work in practice.

The 32 ETH requirement. Running a full Ethereum validator requires staking exactly 32 ETH. This is a significant capital requirement that places solo validation out of reach for most individual investors at Ethereum’s current price. There is no partial validator: it is 32 ETH or nothing for solo operation.

Validator keys. Each validator has two pairs of cryptographic keys: a signing key used for day-to-day validation duties and a withdrawal key that controls the staked ETH. Separating these keys means the signing key can be used on the validator’s online computer while the withdrawal key is kept securely offline, limiting the damage if the signing key is compromised.

Uptime requirements. Validators earn rewards when they are online and performing their duties correctly. They incur small penalties (inactivity leaks) when they are offline or failing to attest correctly. These penalties are small in normal circumstances but accumulate significantly during extended downtime. Running a reliable validator requires a stable internet connection and either monitoring infrastructure or use of a staking service.

Slashing. Slashing is the severe penalty applied to validators that provably misbehave: specifically, proposing conflicting blocks or making conflicting attestations that could be used to justify two different versions of the chain. Slashing results in the immediate loss of a minimum of 1/32 of the validator’s staked ETH plus an additional penalty based on how many other validators are slashed at the same time, reflecting the severity of coordinated attacks. Slashed validators are also forcibly exited from the validator set after a withdrawal delay.

Slashing is distinct from the small inactivity penalties that result from honest validators being offline. It is reserved for provably malicious or doubly-signed behaviour, not for technical failures.

Validator Rewards: How the Economics Work

Validators earn rewards for performing their duties correctly. Understanding the reward structure helps investors evaluate staking returns whether they are running their own validator or using a liquid staking protocol.

Consensus layer rewards. Validators earn ETH for correct attestations, block proposals, and sync committee participation. These rewards are paid from new ETH issuance by the protocol, currently at a rate that produces an annual yield of approximately 3% to 5% on staked ETH depending on the total number of validators, as the yield decreases when more ETH is staked.

Execution layer rewards. When a validator proposes a block, it collects the priority fees (tips) from all transactions in that block. Since EIP-1559, the base fee is burned rather than going to validators, but priority fees remain. Block proposal opportunities are infrequent for individual validators given the large total validator count, but the priority fees collected when a proposal occurs can be significant.

MEV (Maximal Extractable Value). Validators who use MEV-boost software can earn additional income by allowing specialised block builders to construct blocks that extract value from transaction ordering. MEV is a complex area with its own economic and ethical dimensions, but it represents a meaningful additional yield source for validators who participate.

The combined yield from consensus rewards, priority fees, and MEV varies with network activity and the total amount of ETH staked. Higher network usage means more fee income. A lower total staked ETH means higher consensus rewards per validator. The current staking yield is visible on blockchain explorer and staking dashboard tools in real time.

How Individual Investors Access Validator Economics

The 32 ETH minimum for solo validation and the technical requirements of running a validator 24/7 put direct validator operation out of reach for most retail investors. Several options exist for accessing validator economics without running a validator directly.

Liquid staking protocols. As covered in our staking vs farming and popular DeFi protocols explained resources, liquid staking protocols like Lido and Rocket Pool pool ETH from many depositors to run validators collectively, distributing the rewards proportionally. Depositors receive liquid receipt tokens (stETH for Lido, rETH for Rocket Pool) representing their staked position and accruing rewards. These tokens can be used in DeFi while continuing to earn staking yield.

Exchange staking. Many centralised exchanges including Coinbase and Kraken offer custodial ETH staking where the exchange runs validators on behalf of depositors and passes a portion of the rewards after taking a fee. This is the simplest approach but introduces the counterparty risk of the exchange, as covered in our risks of keeping crypto on an exchange resource.

Staking as a service. Providers like Kiln and Figment allow ETH holders with 32 ETH to run a validator using the provider’s infrastructure rather than their own hardware. The depositor maintains control of the withdrawal key while delegating the operational responsibilities to the provider.

Each of these approaches makes a different tradeoff between yield, security, complexity, and decentralisation.

Validators on Other Proof-of-Stake Networks

While Ethereum is the primary reference, other major proof-of-stake networks have their own validator structures worth understanding.

Solana has no minimum stake requirement for validators, though competitive validator economics require significant stake to be profitable. Solana uses a delegated proof-of-stake model where token holders can delegate their SOL to existing validators to share in rewards without running their own infrastructure. This is accessible to any Solana holder and is available directly through most Solana-compatible wallets.

Cosmos-based networks use a delegated proof-of-stake model with a defined active validator set, typically the top 100 to 175 validators by stake. Token holders delegate to active validators and share in rewards. Validators outside the active set don’t earn rewards, creating a competitive dynamic for validator selection.

Avalanche uses a proof-of-stake model requiring 2,000 AVAX to run a validator, with delegators able to stake with existing validators. Like Ethereum, the blockchain consensus mechanism is designed to achieve rapid finality.

Each network’s validator economics, minimum requirements, slashing conditions, and delegation mechanics are specific to that network’s design. Understanding the specific rules before staking on any network is the appropriate due diligence step.

Validator Concentration and Decentralisation Risk

One of the most significant systemic concerns in proof-of-stake networks is validator concentration: the risk that a small number of large validators control a disproportionate share of the network’s staked assets, undermining the decentralisation that makes blockchain networks valuable.

On Ethereum, Lido Finance controls approximately 30% of all staked ETH through its liquid staking protocol, representing the largest single validator concentration in the network. The Ethereum community has engaged in extensive debate about the implications of this concentration for the network’s security and censorship resistance. A single entity controlling more than 33% of staked ETH would have the ability to prevent the network from finalising new blocks, a serious security concern.

This is one of the reasons that validator diversity matters: a network where staked assets are distributed across many independent validators is more secure and more censorship-resistant than one where they are concentrated in a handful of large operators. Rocket Pool’s design, which requires node operators to run their own validator infrastructure rather than delegating to a central pool, explicitly aims to preserve validator decentralisation.

As an investor participating in staking through liquid staking protocols or exchange staking, being aware of validator concentration dynamics and their implications for the networks you’re invested in is part of the broader risk picture covered in our risks of DeFi investing resource.

Tax Treatment of Validator Rewards in Australia

Rewards earned through Ethereum validation or through liquid staking protocols that represent validator economics are generally treated as ordinary income by the ATO at the time of receipt, consistent with the treatment of other staking rewards as covered in our tax implications of staking and yield farming in Australia resource.

The AUD value of ETH or liquid staking token rewards at the time they are received or accrue to your position is assessable income. The subsequent disposal of those reward tokens triggers a capital gains tax event on any gain or loss relative to the income inclusion value.

For solo validators receiving continuous small reward accruals in each epoch, the record-keeping obligation is significant. For liquid staking participants whose stETH balance increases continuously, the tax treatment of the rebasing mechanism is an area where professional advice from a tax accountant familiar with DeFi is particularly valuable. Our cryptocurrency tax Australia and ATO crypto reporting resources provide the broader framework.

Key Takeaways

Validators are the participants who secure proof-of-stake blockchain networks by staking capital as collateral and performing consensus duties including block proposal, attestation, and finalisation. They replaced miners in networks like Ethereum through The Merge, providing equivalent security with dramatically lower energy consumption. Running an Ethereum validator requires 32 ETH, reliable uptime, and technical competence. Individual investors access validator economics through liquid staking protocols, exchange staking, and staking-as-a-service providers. Validator rewards are generally taxable as ordinary income in Australia at receipt. Validator concentration in a small number of large operators is a genuine systemic risk to network decentralisation and security.

Understanding validators provides the foundation for evaluating proof-of-stake networks, assessing the security model of assets you hold, and making informed decisions about how to participate in staking economics.

For everyday investors who want to understand how proof-of-stake networks work and how to generate yield on their Ethereum and other proof-of-stake holdings safely, our Runite Tier Membership provides the education and frameworks to do exactly that. For serious investors who want personalised guidance on staking strategy, validator selection, and integrating proof-of-stake yield into a professionally structured portfolio, our Black Emerald and Obsidian Tier Members receive direct specialist support.

Find out more at shepleycapital.com/membership.

WRITTEN & REVIEWED BY Chris Shepley

UPDATED: MARCH 2026