Ethereum is entering the final testing phase for its highly anticipated Fusaka upgrade, with the mainnet launch slated for December 3, 2025. This upgrade represents a significant step forward in Ethereum's ongoing efforts to improve scalability, security, and efficiency.
The Fusaka upgrade introduces several key improvements to the Ethereum network. A core component of the upgrade is Peer Data Availability Sampling (PeerDAS), a new data verification method. PeerDAS allows validators to verify transaction data by sampling small portions from multiple peers, rather than downloading and storing the entire dataset. This reduces bandwidth and storage requirements for validators, making it easier and cheaper to participate in the network. According to CryptoApis report, PeerDAS slashes bandwidth and storage requirements by up to 70%.
In addition to PeerDAS, Fusaka will increase the block gas limit from 45 million to 150 million gas units. This increase enables Ethereum to process significantly more transactions per block, reducing congestion and lowering transaction fees. Analysts project that this could push Ethereum's throughput to 12,000 transactions per second (TPS) by 2026, rivaling traditional payment systems.
Another notable feature of the Fusaka upgrade is the introduction of Verkle Trees, a storage optimization that replaces Ethereum's current Merkle Patricia Trie structure. Verkle Trees reduce the computational load for nodes by up to 50%, lowering hardware requirements and making it more feasible for smaller entities to run full nodes.
The road to the December 3rd mainnet launch involves rigorous testing on several testnets. Following successful trials on the Holesky and Sepolia testnets, the Fusaka upgrade is scheduled to launch on the Hoodi testnet on October 28, 2025. The Hoodi testnet is designed to closely replicate Ethereum's mainnet conditions, providing developers with a realistic environment to assess the upgrade's performance. Once the upgrade goes live on December 3, the increase in blob capacity will take place two weeks after, putting it around December 17, followed by another blob capacity hard fork on January 7, 2026.
The Fusaka upgrade is part of Ethereum's broader "Surge" phase, with subsequent upgrades like Glamsterdam (2026) set to introduce enshrined proposer-builder separation. This architectural shift enhances transparency and security, addressing institutional concerns about centralization risks in the current builder ecosystem. Moreover, the upgrade's Blob Parameter Only (BPO) forks enable dynamic scaling of blob capacity without full network halts, ensuring Ethereum can adapt to surges in demand.
To ensure a smooth and secure rollout, the Ethereum Foundation has announced a four-week code audit program, offering $2 million to developers who discover and disclose vulnerabilities in the Fusaka codebase. While the Fusaka Upgrade is a net positive, risks remain. Technical delays during testnet phases could disrupt the December 2025 timeline. Regulatory uncertainties, particularly around staking derivatives and institutional custody, also pose challenges. However, Ethereum's rigorous testing process and developer consensus mitigate many of these risks.
The Fusaka upgrade is poised to be a game-changer for Ethereum's institutional adoption. By reducing operational costs, enhancing throughput, and reinforcing deflationary economics, it addresses the core requirements of institutional investors: scalability, security, and efficiency. As the upgrade approaches, the focus will shift to execution – smooth activation and real-world performance will determine its long-term impact.
