Ethereum took a significant step towards a more seamless user experience with the activation of the Fusaka upgrade on December 3, 2025, at 21:49:11 UTC. This upgrade focuses on enhancing the network's scalability, security, and usability, paving the way for wider adoption and a more "instant feel" for users.
Fusaka is a combined execution and consensus layer upgrade. The name "Fusaka" is a blend of Osaka (execution layer) and Fulu (consensus layer). It bundles roughly a dozen Ethereum Improvement Proposals (EIPs). It is the first upgrade fully aligned with Ethereum's unified vision to scale the L1, scale blobs and improve UX.
Scaling and Efficiency Improvements
A key element of the Fusaka upgrade is Peer Data Availability Sampling (PeerDAS). Previously, every full node was required to download and store all "blob" data posted by rollups to the Ethereum base layer. Blobs are temporary data containers that make it cheaper for rollups to publish large batches of transactions. PeerDAS changes this model, distributing blob data uniformly across nodes, with each node responsible for roughly one-eighth of the data. Sampling techniques are then used to allow validators to check random pieces of blob data from their peers. This allows the network to support up to an eightfold increase in blob data throughput for rollups while keeping node bandwidth and storage requirements manageable. PeerDAS reduces bandwidth requirements by 85%, allowing Layer 2 (L2) solutions to publish more blobs at lower costs.
The upgrade also increases the block gas limit from 36 million to 60 million, allowing more transactions to fit within each block. Additionally, Fusaka introduces Blob Parameter Only (BPO) forks, a mechanism for safely increasing blob capacity between hard forks as rollup demand grows. These upgrades collectively contribute to a more scalable and efficient Ethereum network, reducing costs for rollup users.
Enhanced User Experience and Security
Fusaka introduces native support for the secp256r1 elliptic curve through EIP-7951. This is the signing standard used by Apple Secure Enclave, Android Keystore, and most consumer hardware. This enhancement enables passkey-style authentication on Ethereum, allowing wallets and applications to integrate familiar authentication flows like Face ID, Touch ID, and WebAuthn directly. This streamlines onboarding, simplifies recovery processes, and strengthens security for both retail and institutional users.
Impact on Layer 2 Solutions
Fusaka is particularly beneficial for Layer 2 scaling solutions like Optimism, Arbitrum and Polygon. These solutions improve Ethereum's scalability by processing transactions off-chain and then submitting batched results to the mainnet. By increasing data availability and reducing costs, Fusaka empowers L2s to scale more efficiently and offer faster, cheaper transactions to their users.
Looking Ahead
The Ethereum community is already anticipating the next major upgrade, Glamsterdam, expected in early 2026. Fusaka lays the groundwork for Glamsterdam by making block composition predictable and scaling data availability. OP Labs is also preparing a Superchain upgrade in early 2026 to adopt Fusaka EIPs into the OP Stack. These ongoing developments reflect Ethereum's commitment to continuous improvement and its dedication to providing a superior user experience.
