Layer 2 Scaling Solutions for Ethereum


Blockchain’s moon race is on because the ecosystem grapples with growing scalability options to fulfill demand with out sacrificing safety or decentralization – the traditional blockchain trilemma.

The speedy development in decentralized finance, NFTs, and gaming has seen adoption congest the Ethereum community, particularly, resulting in bottlenecks and excessive transaction charges given its capability for processing only some transactions per second, rendering many dApps usable at occasions.

Ethereum’s transition to a proof-of-stake sharded community could alleviate a few of that stress on layer 1, with sharding splitting the Ethereum community into new chains or shards to unfold the load, lowering congestion, and growing transactions per second.

Nevertheless, given full deployment continues to be years away and participation isn’t displaying indicators of slowing down any time quickly, the urgent want for scalable options has accelerated the adoption of layer 2 expertise that runs on high of Ethereum’s layer 1, reasonably than attempting to enhance efficiency on the base layer.

Layer 2 and associated expertise supply a number of totally different options for Ethereum scaling, every with its personal advantages and trade-offs, together with:

  • Plasma
  • Sidechains
  • State Channels and Fee Channels
  • Optimistic Rollups
  • ZK-Rollups
  • Validium
  • Aggregators



Plasma chains are separate blockchains that anchor to Ethereum, generally referred to as baby chains, as they function as smaller copies of the Ethereum mainnet. These baby chains use a mixture of sensible contracts and cryptographic verification to dump transactions from the mum or dad chain.

Every with its personal mechanism for block validation, Plasma chains periodically report again to the Ethereum predominant chain, utilizing its safety to settle disputes when challenged through fraud proofs.

Plasma chains allow excessive throughput at a low value per transaction. Nevertheless, solely fundamental transactions like token transfers and swaps are supported, there’s a liveliness requirement, and chain withdrawals will be prolonged to permit for challenges.

A number of initiatives present implementations of Plasma for dApp integration, together with OMG Community and LeapDAO.

Plasma. Picture by Close


Layer 2 sidechains are unbiased Ethereum Digital Machine (EVM) suitable blockchains working parallel to the Ethereum predominant chain. Validator nodes within the sidechain community are liable for confirming and processing transactions, including blocks, and sustaining the sidechain’s personal consensus guidelines, equivalent to proof-of-authority or delegated proof-of-stake, to offer extra environment friendly transactions.

Compatibility is achieved through a two-way bridge to Ethereum, although its safety shouldn’t be straight inherited and is the duty of the sidechain.

Sidechains. Picture by Close

Sidechains make the most of established expertise and help extra complicated transactions with EVM compatibility, although they’re much less decentralized and depend on their very own consensus mechanisms reasonably than the safety of layer 1 and so aren’t technically layer 2 in that sense.

Initiatives providing sidechain implementations embody POA Community and xDai chain.

State Channels and Fee Channels

One of many first extensively mentioned layer 2 scaling options, state channels use multi-signature contracts to allow individuals to transact shortly and often off-chain, settling again to layer 1 for finality as required.

State channels can handle extra complicated interactions like a sport, whereas cost channels are simplified state channels that solely cope with funds between two individuals. State channels permit for very excessive transaction throughput at a really low value, making them ultimate for micropayments. Nevertheless, the time and price to arrange and settle channels will not be ultimate for one-off funds, liveliness is required, and funds should be locked up in open cost channels.

The primary initiatives leveraging state channels on Ethereum are Celer, Perun, and Raiden.

Optimistic Rollups

Optimistic rollups sit in parallel to the Ethereum predominant chain on layer 2. They permit transactions to be executed cheaply and scalably in batches outdoors layer 1 whereas nonetheless utilizing the safety of the Ethereum base layer when submitting them as a single transaction.

As computation is the sluggish and costly factor of the Ethereum community, optimistic rollups supply as much as 100 occasions scalability improvements as they don’t run any computation by default, a quantity that can improve additional with the longer term introduction of Ethereum sharding.

As an alternative, optimistic rollups assume transactions are legitimate and solely run computation if challenged through a fraud-proof. Optimistic rollups use a bonding system, and anybody confirmed liable for a fraudulent transaction or problem will forfeit their bond with some slashed and a few used to incentivize the proper get together.

Optimistic rollups can deal with something finished on Ethereum layer 1 as they’re EVM and Solidity suitable. As all transaction knowledge is saved on the layer 1 chain, optimistic rollups stay safe and decentralized whereas offering execution scalability. Nevertheless, lengthy wait occasions for on-chain transactions are doable as a result of potential fraud challenges.

Optimistic rollups. Picture by Close

As optimistic rollups help each easy funds and sophisticated sensible contracts, they’re seen as extra instantly appropriate for DeFi functions, with Optimism, Arbitrum, and Cartesi among the many a number of initiatives providing implementations.

In an indication of the longer term course of the house, the main DEX platform Uniswap lately additionally introduced it might be taking the following step in adopting layer 2 tech by launching on Optimism to sharply scale back transaction prices for its customers.


Zero-knowledge rollups, or ZK-rollups, bundle transactions off-chain and generate a cryptographic proof, often known as a SNARK. In distinction to optimistic rollups, ZK-rollups run computation off-chain and submit these validity proofs to the layer 1 chain.

ZK-rollup sensible contracts preserve the state of all transactions on layer 2, which may solely be up to date with validity proof. As ZK-rollups solely want the validity proof reasonably than all of the transaction knowledge, validating a block is faster and cheaper because it consists of much less knowledge and requires much less fuel.

Moreover, because the ZK-rollup contract has already verified the transactions, there are not any delays in transferring from layer 2 to layer 1.

In consequence, ZK-proofs supply quicker finality occasions whereas remaining safe and decentralized because the knowledge wanted to recuperate the state is saved on Ethereum layer 1. Nevertheless, some ZK-rollups do not need EVM help, and validity proofs are intensive to compute, making them unsuitable for dApps with little on-chain exercise.

A number of implementations of ZK-rollups additionally exist, together with zkSync and ZKSwap. zkSync gives a trustless protocol for scalable, low-cost funds on Ethereum utilizing ZK-rollup expertise, serving to crypto wallets and defi platforms to unlock PayPal-like scale. ZKSwap offers a ZK-rollups-based layer 2 DEX with zero fuel charges and high-transaction throughput, reworking the way forward for the AMM mannequin.

Concord’s interoperable layer 2 for Ethereum gives one thing extra distinctive, combining one of the best of each the optimistic and ZK-rollup worlds. Concord offers full EVM compatibility, not like ZK-rollups, quicker settlement with shorter withdrawal occasions in comparison with Optimistic rollups, and gas-efficient interoperability based mostly on its sharded Proof-of-Stake blockchain that bridges to Ethereum through sensible contracts.

By constructing on the advantages of each Optimistic rollups and ZK-rollups, typically seen to be probably the most promising of layer 2 scaling applied sciences, whereas addressing their shortcomings, Harmony can present a extra wholescale resolution for initiatives to deploy. Concord’s interoperability additionally extends past Ethereum with its Horizen bridge to Binance Sensible Chain, opening up entry to the broader defi ecosystem.


Validium makes use of validity proofs like ZK-rollups, however as an alternative, knowledge shouldn’t be saved on Ethereum layer 1, permitting for scalability of as much as 10,000 transactions per second per Validium chain, of which a number of can run in parallel.

Validium gives no withdrawal delays, enhancing capital effectivity, and isn’t weak to sure financial assaults confronted by high-value dApps utilizing fraud-proof-based techniques. Nevertheless, Validium chains have restricted sensible contract help.

Initiatives offering implementations of Validium embody Loopring and StarkWare. Immutable X, the primary layer 2 scaling resolution for NFTs on Ethereum, makes use of StarkWare’s Validium and ZK-rollup expertise to allow transaction speeds of over 9,000 per second with zero fuel charges whereas retaining Ethereum’s safety for its ecosystem of marketplaces, apps, and video games.


Polygon is one thing of an aggregator of those layer 2 options, providing a number of implementations of a number of layer 2 applied sciences. In consequence, Polygon has develop into the fastest-growing layer 2 community, bringing blockchain infrastructure to the plenty by opening up the accessibility, usability, and use instances of decentralized functions on Ethereum’s web of blockchains.

Polygon’s suite of layer 2 scalability options has witnessed adoption from Defi blue chips, with platforms like Aave, SushiSwap, and 1inch already integrating with it.

CVI, the decentralized volatility index for the crypto house powered by the COTI community, has additionally adopted that lead in integrating with Polygon. By processing transactions outdoors of the principle Ethereum chain, CVI customers will be capable to open positions, present liquidity, and stake with lowered fuel charges and quicker execution, together with margin buying and selling on the revamped CVI


Nobody scaling resolution alone is ample to satisfy the safe, decentralized, and scalable imaginative and prescient of Ethereum, avoiding the issue of excessive charges and bottlenecks.

Sharding will definitely assist on-chain scaling on layer 1, however off-chain layer 2 options that may flexibly tailor to the distinctive necessities and acceptable trade-offs of the plethora of dApp initiatives being developed are key to the way forward for blockchain.

The ecosystem as an entire is bigger than the sum of its elements, and totally different layer 2 options can exist and work collectively in concord to reply to the growing calls for of mainstream adoption, persevering with to assist scale back congestion and forestall single factors of failure as we transition to the world of Internet

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