What to Expect From Ethereum’s Fusaka Upgrade?

In brief

• Ethereum’s Fusaka upgrade is expected to be implemented on Wednesday.
• The upgrade implements key features like PeerDAS, which changes how the network collects and verifies data from layer-2 networks.
• The upgrade will increase blob capacity, improving speed and scalability in the Ethereum ecosystem.

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Ethereum builders are optimistic that the Fusaka Upgrade, a major change in how the mainnet collects and verifies data from layer-2 networks, will dramatically improve the network, making rollups cheaper and more scalable.

“That directly supports the ecosystem that most users interact with today,” Nick Johnson, co-founder and lead developer of the Ethereum Name Service told Decrypt .

“It’s also a sign of Ethereum’s maturity; upgrades now focus on refining efficiency, decentralization, and resilience. Fusaka makes the base layer more capable of supporting long-term growth without compromising the properties that make Ethereum reliable in the first place.”

Fusaka, which is short for Fulu-Osaka, follows the network’s May upgrade—Pectra—which enabled new wallet smart contract functionality and improved validator economics on top of network scalability improvements.

The blockchain’s latest upgrade will once more add scaling improvements, this time more specifically by increasing the available blob space in each Ethereum transaction block via the PeerDAS Ethereum Improvement Proposal (EIP-7594).

“PeerDAS—this is really the cornerstone of the fork,” said Ansgar Dietrichs of the Ethereum Foundation in a launch video posted to X. “Under the hood it very fundamentally changes the nature of the chain. It changes how we do these state attestations, to move from this naive data availability mechanism to this sampling based one.”

Blobs were first introduced in Ethereum’s 2024 Dencun upgrade, lowering layer-2 network gas fees by allowing data from the scaling networks to be stored temporarily, instead of permanently.

With Fusaka’s upgrade, blob capacity is expected to increase by as much as 8x.

“Overall, Fusaka is a pivotal step toward an interoperable Ethereum, enabling rollups to operate as one coherent ecosystem under Ethereum’s security, bringing the network closer to its original vision of a decentralized world computer, but unified ecosystem,” Alon Muroch, co-founder of Ethereum staking firm SSV Labs told Decrypt.

Tomorrow: Fusaka

Ethereum’s second major upgrade this year.

→ Feature highlight: PeerDAS - Unlocking up to 8x data throughput. For rollups, this means cheaper blob fees and more space to grow.

Learn more. pic.twitter.com/sEfeiTamy9

— Ethereum (@ethereum) December 2, 2025

Ethereum co-founder Vitalik Buterin previously called the functionality unlocks enabled by PeerDAS “unprecedented,” ultimately noting that it is the "key to layer-2, and eventually layer-1 network scaling.

Fusaka will fix this.

But also, safety first is of the utmost importance for Fusaka. The core feature, PeerDAS, is trying to do something pretty unprecedented: have a live blockchain that does not require any single node to download the full data.

The way PeerDAS works is that…

— vitalik.eth (@VitalikButerin) September 24, 2025

The network’s next major upgrade, Glamsterdam, is in development for 2026. Its key features include scaling the layer-1 network and blobs.

ETH is up nearly 10% on Tuesday, now changing hands at $3,020. The second-largest crypto asset by market capitalization has jumped around 4.3% in the last 7 days, but remains nearly 39% off its August all-time high of $4,946.

Despite the asset’s daily gain, predictors on Myriad still believe it’s more likely that ETH will fall to $2,500 before jumping to $4,000.

(Disclaimer: Myriad is a product of Dastan, the parent company of an editorially independent Decrypt .)