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Ethereum accelerated: Fusaka

What is Fusaka?

The 17th major upgrade to Ethereum comes just about seven months after the Pectra update broadly transformed the protocol. The successful deployment of Fusaka brings the now decade-old project into a new era of maturity, with Ethereum core developers now aiming to roll out hard forks on an accelerated twice-a-year cadence.

Fusaka maintains the naming convention of tying the execution layer upgrade to an earthly city (Osaka this time around) while consensus layer improvements give a nod to a heavenly body (the star Fulu in this case). Fusaka’s enhancements don’t include the dramatic user experience innovations or staking modifications seen in Pectra, but rather focus on backend boosts to enable some of the biggest gains in network scaling since the Merge in 2022.

This is a major milepost on the Ethereum roadmap as it continues to wind through The Surge and beyond. The Surge phase focuses on scalability via rollups to allow for vastly more user activity and transactions as well as better data availability to ensure the information needed to verify those transactions is reliably accessible to everyone running the network (node operators).

What’s changing:

The three pillars of the Fusaka upgrade

Real Scaling Capacity

Fusaka’s key optimization is a significant increase in scaling capacity via PeerDAS (Peer Data Availability Sampling), which essentially removes the requirement that all nodes download and store all blob data (blobs are a form of temporary data storage introduced as part of the Dencun update to boost Ethereum’s scalability and efficiency). This is Ethereum’s introduction to Danksharding, eventually enabling orders of magnitude more data throughput at vastly lower transaction costs.

Network Efficiency and Security

The upgrade package also increases the block gas limit and introduces a cap on gas per transaction meant to improve network efficiency and security. The higher gas ceiling immediately boosts the execution bandwidth for all users and developers. It is deliberately introduced at the same time as the new per transaction gas cap so that, even as throughput increases, the network remains safe from single-transaction denial-of-service attacks.

Foundation for Parallel Execution

Fusaka sets the stage for Ethereum’s next upgrade, Glamsterdam, which will bring parallel transaction processing. By making block composition predictable and scaling data availability, Fusaka creates the conditions for Ethereum to handle higher throughput without compromising decentralization.

How users benefit

The changes included in Fusaka are carefully designed and implemented by the global Ethereum developer community, working in public and in active dialogue with researchers, client teams, and validators. Each upgrade undergoes community feedback and meticulous planning before mainnet activation.

Fusaka’s dozen EIPs have undergone three successful testnet runs in recent months, completing with the last validation on the Hoodi testnet that began in late October. Now mainnet activation is planned for December 3, 2025.

  • More transactions in every block = faster service and lower fees.

  • Easier access for L2s and apps with no expensive hardware upgrade.

  • Robust security even as the network scales.

The most significant changes in Fusaka:

Scaling Rollup Efficiency with EIP-7594: Introducing PeerDAS

EIP-7594, PeerDAS, is critical for scaling Ethereum’s Layer 2 throughput while keeping the hardware and bandwidth requirements for full nodes tenable. PeerDAS addresses the resource-intensive problem of every full node needing to store every blob by implementing Data Availability Sampling (DAS). Blobs are uniformly randomly distributed across nodes in the network.

This change is essential for maintaining network robustness as blob throughput dramatically increases. Fusaka is expected to enable theoretical scale up to 8x the current blob capacity.

"PeerDAS will allow many nodes on the network to store less data from blobs, and allow us to increase the data available in blobs at the same time. Prior to PeerDAS all nodes had to store all of the blob data, and this is no longer a requirement."

Paul Harris
Senior Staff Blockchain Protocol Engineer at Consensys

Unlocking Higher Throughput with EIP-7935 & EIP-7825: Gas Limit Changes

Fusaka introduces gas limit changes that improve network efficiency and security.

  • The default block gas limit is set to rise, targeting 60 million gas. This is an intentional move toward consistent scaling.

  • Crucially, EIP-7825 introduces a Transaction Gas Limit Cap of 16.78 million gas. This limit is a proactive DoS hardening measure that ensures no single transaction—even large smart contract deployments or complex DeFi operations can consume an entire block, making the network more resilient.

"With EIP‑7935, each Ethereum block can now include more transactions. More transactions per block means the network can support more activity at once, faster, cheaper, and more reliably."

Gabriel Trintinalia
Protocol Engineer at Consensys

Advancing Web3 UX with EIP-7951: Passkey Support

EIP-7951 delivers a major UX upgrade by introducing support for the secp256r1 curve, which unlocks device-native signing and passkeys. Wallets can tap into hardware security modules (HSMs) and FIDO2/WebAuthn directly. This fundamental shift enables smoother onboarding, easier recovery, and multi-factor flows that resemble modern apps without requiring a seed phrase.

"By supporting hardware-backed signing, EIP‑7951 helps developers enhance security and user experience
without the complexity or expense of verifying signatures on-chain."

Gabriel Trintinalia
Protocol Engineer at Consensys

What else is included in Fusaka

EIP-7939

Count Leading Zeros (CLZ) Opcod

Makes certain math operations faster and cheaper for developers.

This EIP adds a new instruction to the Ethereum Virtual Machine that returns the number of zeros at the start of a 256-bit number. It allows for more efficient arithmetic and bytecode reductions while saving gas in smart contracts.

EIP-7918

Blob Base-Fee Bounded by Execution Costs

Helps keep transaction fees fair and adaptive to network congestion.

This EIP ensures Layer 2s pay a proportional fee whenever their activity spikes compute demand on nodes. It links the blob base-fee (charged for storing large data objects) to execution gas, preventing fee market anomalies.

EIP-7934

RLP Execution Block Size Limit

Reduces the risk of network delays and attacks from oversized blocks.

Sets a maximum block size of 10 MiB for execution payloads, helping keep propagation and validation times predictable. This change lessens the chance for chain reorganizations or denial-of-service scenarios.

EIP-7910

eth_config JSON-RPC Method

Makes it easier for monitoring tools and validators to check network settings.

Standardizes a JSON-RPC method allowing external tools to query a node's configuration, ensuring validators are correctly synchronized at major forks and upgrades.

EIP-7883

MODEXP Gas Cost Increase

Prevents a single transaction from clogging the network by better pricing a specific complex calculation.

It raises the gas cost for the MODEXP (modular exponentiation) precompile so its usage more accurately reflects the actual computational resources needed. This change protects the network from transactions that monopolize block processing time.

EIP-7892

Blob-Parameter-Only Forks (BPOs)

Allows Ethereum to safely and gradually increase network data capacity between big upgrades.

BPOs introduce a process for adjusting the number of blobs (large data containers) independently from major network forks. This makes future scaling smoother and more adaptive as demand grows.

EIP-7917

Deterministic Proposer Lookahead

Helps the network know who is proposing blocks ahead of time.

The Beacon Chain now "sees" upcoming block proposers further in advance, enabling features like preconfirmations and improving overall network coordination.