If you have ever used Ethereum in the last couple of years, you have probably wondered why gas fees were very high per transaction at one point in time. In 2025,  however, that feeling has finally pushed the majority of activity off mainnet and onto Layer 2 (L2) networks like Optimism, Arbitrum, zkSync Era and Base. This caused the fees to fall, real brands to show up and L2s to stop being a niche scaling story and became where Ethereum actually happens.

This post walks through why L2s exploded, what separates Optimistic vs ZK rollups, a quick tour of the big four as well as provides some guidance on which L2 is right for you.

Why did Layer 2s blow up in 2025?

Ethereum upgrades that made L2s very cheap

The Dencun upgrade which rolled out on March 13, in 2024 was designed to make L2s cheaper and more scalable. This was made possible by introducing data blobs via EIP‑4844. One year later, the results were dramatic as the average Ethereum gas fees dropped about 95%, from 72 gwei in 2024 to 2.7 gwei by March 12, 2025. And also, an average swap that once cost around $86 now costs roughly $0.39. As for NFT sale costs? They fell from about $145 to $0.65.

Most of that benefit accrues to rollups, which now post data much more cheaply. In practice, it has become so inexpensive to transact that for many users, there is no reason to use Ethereum L1 for day‑to‑day transactions.

TVL and usage migrated to L2

By late 2024, Ethereum L2s had already hit around $51.5 billion in total value locked (TVL), which is a 205% jump from November 2023. And, Arbitrum and Base were leading the surge. That growth set the stage for 2025. And in 2025, Arbitrum kept its lead in TVL and active addresses while Base rapidly climbed into the number‑two spot, powered by memecoins and high‑throughput retail activity. Optimism’s Superchain on the other hand which is a family of OP Stack rollups including Base, World Chain, Ink, Soneium, Unichain and others came to handle about 60% of all Ethereum L2 transactions. And it led with 11.5M daily transactions and more than $4B in TVL across OP‑Stack chains by early 2025. 

In other words, the center of gravity for Ethereum users, liquidity and apps is now on Layer 2 networks.

Major brands picked up their Layer 2 stakes

The year of 2025 also cemented the idea that traditional brands run on L2. Kraken, Sony, Coinbase and Uniswap all chose Optimism’s OP Stack to power their own L2 networks like Ink, Soneium, Base, Unichain, World Chain, etc. This helped OP Stack become the default franchise kit for new rollups. On the other hand Robinhood announced it is building its own L2 network on Arbitrum, and this will be optimized for tokenized stocks and other assets. 

When exchanges, consumer apps and enterprises choose a stack, it tends to stay chosen for a long time. That is part of the reason why Layer 2 positioning in 2025 really matters.

Optimistic vs ZK Rollups

All of these Layer 2s are rollups. That is they batch lots of transactions off‑chain and then post compressed data to Ethereum. And that is how they cut fees and increase throughput.

They only differ on how they prove those batches are valid

Optimistic rollups (Optimism, Arbitrum, Base)

These rollups assume that transactions are correct by default. There is a challenge window often  around 7 days, where anyone can submit a fraud proof if something looks wrong. 

Their advantage is that they have very strong EVM compatibility. That is solidity, existing Ethereum tooling and infrastructure which is mostly just work. They are great for general‑purpose DeFi, gaming, social and governance. Most of the current Ethereum apps can deploy with minimal changes.

The disadvantages however, are that withdrawals to Ethereum L1 are slow unless you use a fast bridge. Also, their security relies on honest actors watching the chain and submitting fraud proofs.

ZK rollups (zkSync Era, Linea, Starknet, Scroll)

These rollups use zero‑knowledge proofs to mathematically prove that every batch is valid before it’s accepted on Ethereum. 

Their advantage is that they have fast finality, which means that they have very strong security guarantees and excellent data compression. They are mainly better suited to privacy‑sensitive or high‑volume institutional use cases over the long term.

Their disadvantage however, is that they are more complex to build, and full EVM equivalence is newer and still maturing. Also, tooling is improving quickly, but not yet as drop‑in as Optimistic rollups.

The rule of thumb is that if you want maximum compatibility and easy deployment today, then you must start with Optimistic rollups. But, if you prefer cutting‑edge performance, privacy or ZK‑native designs  and you’re okay with newer tooling?  Then you must explore ZK rollups like zkSync Era.

The Big 4 Layer 2s in 2025 

Arbitrum is the TVL leader among L2s with deep liquidity, a huge DeFi ecosystem and strong traction in gaming. Analyses through 2025 consistently show Arbitrum near the top in both TVL and weekly active addresses. Arbitrum is best for DeFi traders, yield farmers and power users who want lots of protocols and liquidity with Ethereum‑like UX.

Optimism is not  just an L2 as it is an open‑source stack (OP Stack) that powers a whole ecosystem of rollups known as the Superchain. These include Base, Ink (Kraken), Soneium (Sony), Unichain (Uniswap), World Chain and the privacy‑focused Silent Data. By early 2025, the Superchain processed about 60% of all Ethereum L2 transactions, targeting 80% by year‑end. And in August 2025, Optimism partnered with Flashbots to improve sequencing, bringing near‑instant confirmations and fairer transaction ordering across OP‑Stack chains. Optimism and OP stake are best for users and builders who want network effects (many L2s sharing tools and liquidity) and care about open governance and public‑goods funding.

Base is Coinbase’s L2, which is tightly integrated into its exchange and wallet experience. That makes it a natural first stop for newcomers. By late 2024 it had become the second‑largest L2 by TVL and even briefly hit 106 transactions per second, largely due to the memecoin mania. In December 2025, Base launched a Chainlink‑secured bridge to Solana using CCIP. This allowed users to move SOL and Solana assets into Base and give Base dApps native access to Solana tokens. This is best for everyday users who want cheap, fast transactions and a smooth Coinbase‑style UX, and those builders targeting mainstream audiences.

zkSync Era is a ZK‑rollup built on its own ZK Stack and Elastic Network vision. This is a future web of interconnected ZK chains. In March 2025, zkSync shut down its Ignite liquidity program which had pushed TVL above $270M to refocus on Elastic Network and interoperability. In January 2026, Matter Labs announced that zkSync Lite, the original ZK rollup deployed in 2020, will be deprecated in 2026. This is a sign the team considers Era and the newer architecture  are ready for prime time. zkSync Era is best for users and devs who want cutting‑edge ZK tech, strong security and an interoperability‑first roadmap. They must also be comfortable building in a fast‑moving ecosystem.

Final thoughts and conclusion

For DeFi traders and yield farmers, starting with Arbitrum and Base makes more sense as they have the depth of liquidity and protocol variety. However, they must also keep an eye on Optimism Superchain aligned DeFi. Casual users who want cheap and simple user experience, Base and Optimism are the defaults. And for those who prefer privacy and institutional grade infrastructure, then zkSync Era and emerging ZK-based app chains are the target. As for builders choosing stacks, those who need faster time to market solutions with existing Ethereum tooling should look at optimistic rollups. And those who want to be early in ZK multi-chain ecosystems must explore zkSync Era and the ZK Stack.

The biggest 2025–26 trend in L2s is cross‑rollup interoperability. OP’s Superchain messaging, Base’s Solana bridge, and zkSync’s Elastic Network all point toward a future where your choice of L2 feels is less like picking a walled garden and more like choosing a home base in a connected multichain world.

References

Martin Young – “Solana and Coinbase’s Base connect together using Chainlink” (Cointelegraph, Dec 5, 2025) https://cointelegraph.com/news/coinbase-base-solana-connect-together-using-chainlink

Jesse Coghlan – “Ethereum’s first ZK-rollup, ZKsync Lite, to be retired in 2026” (Cointelegraph, Jan 2026) https://cointelegraph.com/news/ethereum-zk-rollup-zksync-lite-sunset-2026

Margaux Nijkerk – “Optimism Taps Flashbots to Supercharge OP Stack Sequencing” (Coindesk, Aug 21, 2025) https://www.coindesk.com/tech/2025/08/21/optimism-taps-flashbots-to-supercharge-op-stack-sequencing

Will Canny – “Silent Data Becomes First Privacy-Focused Layer 2 to Join Ethereum’s Superchain” (Coindesk, Sept 3, 2025)
https://www.coindesk.com/tech/2025/09/02/silent-data-becomes-first-privacy-focused-layer-2-to-join-ethereum-s-superchain

Margaux Nijkerk – “Linea to Burn ETH With Every Transaction in Bold L2 Upgrade” (Coindesk, Jul 29, 2025) https://www.coindesk.com/tech/2025/07/28/linea-to-burn-eth-with-every-transaction-in-bold-l2-upgrade