What The Heck Are Confirmation Layers?

I already know why you are here, so let’s skip the polite intro and jump right into this. But first, some background on why we even need these layers.

Layer 2s (L2s) are incredibly fast at processing transactions, but there's a gap between when something happens on an L2 and when you can actually trust it's final.

This creates real problems for anyone trying to build applications that work across multiple chains. And that's why we have confirmation layers: solutions that will change how different chains work with each other forever.

We Have A Problem: Speed vs. Trust in Layer 2s

Layer 2 solutions have solved Ethereum's scalability problem beautifully: they can process thousands of transactions per second.

While L2s can sequence and execute transactions in seconds, it typically takes 15+ minutes (or even hours) for those transactions to achieve true finality on Ethereum's Layer 1.

This creates several critical problems:

The Finality Gap

When an L2 processes a transaction, it's initially just the sequencer (usually a single entity) saying, "this happened." Other chains, exchanges, and applications can't safely act on this information because:

• The sequencer could be inaccurate

• The transaction might get reorganised out of existence

• The final settlement on L1 might not match what the L2 initially claimed

Cross-Chain Paralysis

This uncertainty is devastating for crosschain applications. Imagine you want to:

• Move assets between L2s quickly

• Use intent-based systems that execute across multiple chains

• Run arbitrage strategies that depend on multiple L2 states

• Build applications that aggregate liquidity from various L2s

Currently, you have two bad choices:

1. Wait 15+ minutes for L1 finality (slow and frustrating)

2. Act on unconfirmed L2 state (fast but risky)

Sequencer Equivocation

Most L2s today use centralised sequencers, which creates another problem: sequencer equivocation. This is when a sequencer tells different parties different things about the same block.

For example, a malicious sequencer might:

• Tell Chain A that a transaction happened

• Tell Chain B that it didn't happen

• Submit yet another version to the L1

Without a reliable way to confirm what actually happened, other systems can't safely integrate with L2s. See why we need confirmation layers now? Yes, you do.

What Are Confirmation Layers?

A confirmation layer is specialised infrastructure that sits between L2s and L1, providing fast, reliable confirmations of L2 state without waiting for full L1 finality.

Let's call it a trusted intermediary that can quickly vouch for what's happening on various L2s.

Here's what confirmation layers do:

• Receive blocks from L2s before they're published to L1

• Quickly confirm their validity using fast consensus mechanisms

• Provide immutable commitments that other systems can trust

• Enable safe cross-chain operations based on these confirmations

Now this is very important: confirmation layers don't execute or verify transactions. They simply confirm that the blocks L2s have created are valid and consistent.

Again, Why Do We Even Need Confirmation Layers?

Modular Infrastructure Philosophy

The blockchain space is moving toward modularity, where each component is optimised for specific functions. Ethereum excels at security and decentralisation but sacrifices speed.

L2s excel at speed but sacrifice immediate finality. Confirmation layers fill the gap by providing the speed needed for crosschain communication while maintaining security.

Enabling True Interoperability

We all dream of a multichain future. I know you do. But it requires seamless communication between L2s. Without confirmation layers, each L2 is essentially isolated until its transactions finalize on L1. This makes building integrated crosschain applications nearly impossible.

Economic Efficiency

Waiting 15+ minutes for finality is economically inefficient. Confirmation layers help us save money (yes, proof time is money) by enabling safe and fast crosschain operations.

How Confirmation Layers Work: Technical Mechanics

Basic Flow

1. L2 Block Creation: L2s sequence and execute transactions as usual, creating blocks.

2. Submission to Confirmation Layer: Instead of immediately publishing to an L1, L2s first send their blocks to the confirmation layer.

3. Fast Consensus: The confirmation layer uses a fast consensus mechanism (typically Byzantine Fault Tolerant consensus) to confirm the block in seconds.

4. Immutable Commitment: Once confirmed, the block becomes immutable. The L2 can only settle blocks on L1 that match what was confirmed.

5. Crosschain Visibility: Other chains and applications can now safely act on the confirmed state.

Byzantine Fault Tolerant (BFT) Consensus

Most confirmation layers use BFT consensus protocols, which can reach agreement quickly as long as fewer than one-third of participants are malicious.

This provides:

• Speed: Consensus in seconds rather than minutes

• Security: Cryptographic guarantees about block validity

• Finality: Once confirmed, blocks cannot be changed

State Derivation

Anyone can use confirmation layer data to derive the current state of connected L2s. As long as they trust the confirmation layer, they can trust that this derived state will match the eventual L1-finalised state.

Espresso: A Confirmation Layer on Ethereum Saving The Day

Espresso Network exemplifies how confirmation layers work in practice. Don’t know what Espresso is? I wrote a really, really simple guide here.

Anyway, here's how Espresso operates:

Technical Architecture

• HotShot Consensus: Espresso uses a custom-designed BFT consensus protocol called HotShot to optimise for speed without sacrificing decentralisation

• Sub-10 Second Confirmations: Blocks are confirmed in under 10 seconds (targeting ~6 seconds)

• Permissioned to Permissionless: Launched with a permissioned validator set but transitioning to permissionless proof-of-stake

Integration Process

When chains integrate with Espresso:

1. They continue sequencing their own blocks normally

2. They send these blocks to Espresso for confirmation before L1 submission

3. Espresso confirms the blocks using HotShot consensus

4. Only blocks that match Espresso's confirmations can be settled on L1

5. This prevents sequencer equivocation and provides fast finality

Security Model

Espresso maintains integrity as long as two-thirds of its nodes are honest. The upcoming transition to proof-of-stake will add economic security, making attacks expensive and self-defeating.

How’s Espresso Useful In The Real World?

Centralised Exchanges (CEXs)

CEXs can now act on Espresso confirmations in ~6 seconds, rather than waiting 15 minutes or more for L1 finality. This means:

• Faster deposits and withdrawals

• More responsive trading experiences

• Reduced operational risk from pending transactions

Intent-Based Systems

Intent-based protocols can use Espresso to:

• Fulfil crosschain orders securely in seconds

• Avoid the choice between slow execution (waiting for finality) or risky execution (acting on uan nconfirmed state)

• Enable more sophisticated crosschain strategies

Crosschain Arbitrage and Rebalancing

Traders and protocols can:

• Rebalance portfolios across chains more frequently

• Capture arbitrage opportunities that would disappear during 15-minute finality windows

• Build more responsive Automated Market Makers (AMMs)

Application Developers

Developers can build applications that:

• Aggregate state from multiple L2s safely

• Provide real-time crosschain experiences

• Avoid the complexity of managing multiple finality assumptions

Preventing Invalid Proofs

Espresso helps prevent scenarios where:

• Provers use incorrect data because they acted on an unconfirmed L2 state

• Aggregators bundle invalid proofs due to sequencer equivocation

• Crosschain applications make decisions based on state that later gets reorganised

How Do Confirmation Layers Like Espresso Improve Crosschain Infrastructure?

Composability Without Fragmentation

Confirmation layers enable true composability between separate L2s. Instead of each L2 being an isolated silo, they can work together as components of a larger, integrated system.

Trust Minimization

By providing cryptographically secure confirmations, confirmation layers like Espresso reduce the trust assumptions required for crosschain operations. Users don't need to trust individual sequencers. They only need to trust the confirmation layer's consensus mechanism.

Network Effects

As more L2s integrate with the same confirmation layer, the network effects compound. Each new integration enhances the entire ecosystem's value and interoperability.

The World Will Say Yes to Confirmation Layers

As the L2 ecosystem continues to grow, confirmation layers will become essential infrastructure: highways that connect our multichain cities.

These layers solve real problems that exist today while laying the foundation for more sophisticated crosschain applications tomorrow.

Confirmation layers are still an emerging technology, but early implementations such as Espresso are already demonstrating their potential to unlock crosschain interoperability at the speed and scale that modern applications demand.

If you want to know more about Espresso and how their confirmation layer is (seriously) saving the day, you can access their documentation here. Follow them on X to keep up with the caffeinated future they are building!