Fusaka is an upcoming hard fork and major network upgrade for the Ethereum blockchain, tentatively scheduled for release in November 2025. This upgrade aims to enhance the network's efficiency, scalability, and security, building upon previous improvements introduced in earlier hard forks such as Pectra. ^[1]

Overview

The Fusaka hard fork represents the next significant step in Ethereum's ongoing development roadmap, following approximately six months after the Pectra upgrade in May 2025. Its primary objective is to improve the overall performance and resilience of the Ethereum network by focusing on backend enhancements rather than user-facing features. The upgrade bundles a set of Ethereum Improvement Proposals (EIPs) designed to optimize core protocol functions related to scalability, node health, and efficiency, leaving existing smart contracts untouched. ^{[20] [21]}

Technology

The Fusaka upgrade is anticipated to include 11 Ethereum Improvement Proposals (EIPs) aimed at enhancing the network's capabilities. A key proposal among these is EIP-7825, which is designed to bolster network resilience against malicious transaction spam while also contributing to overall scalability improvements. ^{[20] [3]}

However, not all initially considered proposals will be part of the Fusaka release. EIP-7907, which aimed to double the contract code size limit and introduce gas metering, has been excluded to streamline the testing process and avoid potential delays. Similarly, the controversial EVM Object Format (EOF) upgrade, which proposed an overhaul of the Ethereum Virtual Machine (EVM) to simplify smart contract development, was officially removed from Fusaka due to technical uncertainties and community pushback regarding its complexity and implications. The decision to remove EOF was made to prioritize other critical features like PeerDAS, which focuses on enhancing Ethereum's scalability and data availability, and to ensure the upgrade's timeline is not jeopardized. ^{[20] [4] [5] [6]}

A significant proposed change included in Fusaka is the increase of the Ethereum gas limit. EIP-7935 lays the groundwork for this increase, with an initial target of around 45 million and a long-term goal of scaling toward 150 million. This adjustment is intended to enhance network throughput and support more complex operations, potentially reducing transaction costs and improving scalability. ^{[1] [20]}

Key Ethereum Improvement Proposals (EIPs)

Fusaka bundles 11 infrastructure-level EIPs that refine scalability, improve efficiency, and harden the network without breaking existing contracts. The key proposals include:

• EIP-7594 (PeerDAS): A major scalability enhancement that introduces peer data availability sampling. This allows nodes to verify data availability without downloading entire data blobs, which lightens the load on nodes and boosts rollup performance.
• EIP-7825 (Spam Resistance Checks): Prevents malicious transaction spam by capping the gas limit for individual transactions, helping nodes remain stable under high demand.
• EIP-7823 (MODEXP Parameter Limit): Strengthens Ethereum’s resilience to denial-of-service (DoS) attacks by capping the input sizes for the MODEXP precompile, which is used for modular exponentiation.
• EIP-7883 (MODEXP Gas Cost Adjustment): Adjusts the gas pricing for heavy cryptographic operations to better reflect their computational cost, improving network efficiency.
• EIP-7892 (Blob Parameter-Only Forks): Creates a framework for making lightweight, future adjustments to blob parameters without requiring a full hard fork, streamlining future upgrades.
• EIP-7917 (Deterministic Proposer Lookahead): Precomputes block proposers to streamline the validation process, which is particularly useful for rollups and staking operations.
• EIP-7918 (Blob Base Fee Bound): Links blob fees to execution costs, creating a fairer and more predictable pricing mechanism for data blobs.
• EIP-7934 (RLP Execution Block Size Limit): Imposes an upper limit on the size of encoded blocks to limit network bloat and support scalability without breaking compatibility.
• EIP-7935 (Default Block Gas Limit): Outlines the plan to increase the block gas limit, starting around 45 million and scaling toward 150 million, to enable more transactions per block.
• EIP-7939 (CLZ Opcode): Adds a "count leading zeros" instruction to the EVM, which is useful for cryptography, compression, and other bit-level optimizations.
• EIP-7951 (secp256r1 Precompile): Introduces native support for the P-256 elliptic curve, a widely used standard in Web2 security, bridging Ethereum closer to established security standards and wallets.

This set of EIPs was finalized after an EIP freeze on August 1, 2025, to ensure a focused and testable upgrade. ^{[20] [21]}

Development and Timeline

Preparations for the Fusaka hard fork have been actively underway, following an aggressive but deliberate development schedule. The process has involved multiple development networks (devnets) to test and refine the included EIPs. After an initial devnet, Fusaka Devnet 2 launched on June 27, 2025, serving as a "bug-hunt" to identify issues, which was followed by Devnet 3 to test the "happy-path" scenario. A final devnet was launched on July 23, 2025, with public testnets scheduled to follow. ^{[1] [21]}

Despite the ambitious timeline, some members of the Ethereum community have expressed concerns about meeting the proposed launch date. Nixo, an Ethereum protocol support member, noted the tight schedule required to ship the upgrade before Devconnect, emphasizing the need for client releases within a short timeframe. The development roadmap includes plans for successful testnets, bug bounty programs, and stress tests, which are expected to be crucial indicators of the network's readiness for full deployment. ^{[9] [7]}

Testnet and Mainnet Launch

The testnet deployment schedule for the Fusaka upgrade includes Holesky on September 29, followed by Sepolia on October 13 and Hoodi on October 27. Developers are targeting a mainnet launch between November 5 and November 12, pinned to a specific block height that lands just before the Devconnect event, which is set to take place from November 17–22 in Buenos Aires, Argentina. Mainnet activation will only proceed once all testnets have upgraded successfully and analysis from the final devnet confirms the network is operating as expected. ^{[20] [8] [17]}

Security Audit Contest

To bolster security ahead of the mainnet launch, the Ethereum Foundation announced a $2 million audit contest for the Fusaka upgrade. ^[17] The contest, co-sponsored by Gnosis and Lido and hosted on the Sherlock platform, began on September 15, 2025, and runs for four weeks until October 13. ^{[22] [18]} Gnosis contributed $100,000 and Lido contributed $25,000 to the prize pool. The competition invites security researchers to identify vulnerabilities in the upgrade's codebase, with a 2x points multiplier for valid findings in the first week and a 1.5x multiplier in the second week to incentivize early discoveries. ^[22] However, some observers questioned the timing of the contest, noting that developers were still actively identifying bugs on the devnets. ^[17]

Impact on Users and Developers

For developers, Fusaka is designed to be a non-disruptive upgrade. None of the included EIPs are intended to break existing smart contracts or interfaces, ensuring that decentralized applications (dApps) and clients remain fully compatible. The primary benefits for builders come from the increased gas limit, which allows for more transactions and more complex operations within a single block, and the performance improvements from PeerDAS, which will particularly benefit rollups. ^[20]

For everyday users, the improvements from Fusaka will be subtle but noticeable. The upgrade is expected to lead to steadier gas fees and smoother transaction flow, especially during periods of high network traffic. By focusing on the core engine of Ethereum, Fusaka aims to deliver a more stable and efficient experience without requiring any action from users. ^[20]

Future Upgrades

Following Fusaka, attention is already turning to the subsequent Ethereum upgrade, codenamed Glamsterdam. Proposed features for Glamsterdam were expected to be confirmed during the AllCoreDevs – Execution meeting on August 1. One notable proposal for Glamsterdam, put forth by Ethereum core developer Barnabé Monnot, suggests halving Ethereum's block time from 12 seconds to six seconds. If adopted, this change could significantly enhance the performance and user experience of decentralized applications (dApps) and is currently slated for inclusion in the Glamsterdam upgrade, which is anticipated in 2026. ^{[1] [10] [2]}

Regulatory Discussions

In parallel with the technical developments, the U.S. Securities and Exchange Commission (SEC) recently engaged in discussions with key blockchain industry stakeholders, including representatives from Ethereum-aligned organizations such as the ERC-3643 Association, Chainlink Labs, the Enterprise Ethereum Alliance, and LF Decentralized Trust. The meeting focused on exploring potential token standards that could facilitate the compliant issuance and transfer of tokenized securities.

The discussions primarily revolved around integrating open standards like ERC-3643 and compliance frameworks such as Chainlink’s Automated Compliance Engine (ACE) into the existing regulatory landscape. ERC-3643 is a token standard designed for compliant capital markets on Ethereum, while Chainlink’s ACE provides a smart-contract-based compliance framework for managing tokenized assets, including securities and real-world assets.

Dennis O’Connell, president of the ERC-3643 Association, indicated that the meeting signaled a notable shift in the SEC's approach, demonstrating increased engagement and a willingness to understand how blockchain standards can align with regulatory oversight. He noted that the discussions helped illustrate how standardized frameworks could enable regulatory compliance while fostering innovation.

Following the meeting, SEC Chair Paul Atkins suggested that the agency is considering an "innovation exemption" within its regulatory framework to support tokenization. Atkins acknowledged the inevitable migration of assets onto blockchain networks and indicated that the SEC might implement changes to accommodate new trading methods tailored for tokenized securities. ^{[11] [12] [13] [14]}

Economic Considerations

The proposed increase in the Ethereum gas limit to 45 million has garnered significant support from validators, with Ethereum co-founder Vitalik Buterin noting that nearly 50% of staked ETH has signaled in favor of this change. This increase, from the current cap of 37.3 million, is expected to help reduce transaction costs and improve network scalability. However, some community members have raised concerns that a substantial increase in the gas limit could potentially lead to greater network centralization. A larger gas limit raises storage and bandwidth demands, which could strain smaller solo validators who may struggle to meet the new hardware requirements of the blockchain, potentially nudging the network toward a heavier reliance on industrial-scale operators. ^{[15] [16] [20]}

In the broader market context, Ethereum's price recently reached a seven-month high of $3,745, marking a 27% increase in a week due to strong investor accumulation. Over 317,000 ETH, valued at more than $1.18 billion, were removed from exchanges in July, indicating a holding trend and reduced market supply. On-chain metrics, such as the Network Value to Transactions (NUPL) ratio entering the "belief-denial" zone, suggest that holders are beginning to realize profits, which historically can precede short-term corrections.

The Fusaka upgrade is also viewed as a critical development for Ethereum's competitive standing in the broader cryptocurrency market, particularly during periods known as "alt-seasons" when investment flows into alternative tokens. ^[19] As capital rotates into high-beta tokens on rival blockchains, Ethereum faces pressure to maintain its dominance. The success of Fusaka, especially its core innovation PeerDAS, is expected to enhance scalability and reduce transaction costs, reinforcing Ethereum's role as the primary settlement layer for decentralized applications. A successful implementation could help anchor market flows to the Ethereum ecosystem, though execution risks and potential delays remain a concern. ^[19]