Ethereum Fusaka & Glamsterdam Upgrade Guide 2026

1. What is Fusaka?

Fusaka is a major Ethereum upgrade that went live on December 3, 2025. It represents the convergence of two parallel protocol improvements: Fulu on the consensus layer and Osaka on the execution layer. The name combines these two upgrades to reflect Ethereum’s continued emphasis on coordination between consensus and execution improvements.

Fusaka is the third major upgrade in Ethereum’s current roadmap, following Dencun (March 2024) and Pectra (May 2025). It contains 12 Ethereum Improvement Proposals (EIPs) focused on scaling, data availability, and network efficiency. The upgrade underwent three successful testnet deployments before launching on mainnet, ensuring stability and security.

The upgrade is named after neighborhoods in Japanese cities, following Ethereum’s tradition of naming upgrades after real-world locations. Fusaka represents a critical milestone in Ethereum’s “Surge” roadmap, which prioritizes scaling Layer 2 solutions and dramatically reducing transaction costs for end users.

2. PeerDAS: The Game-Changer (EIP-7594)

PeerDAS (Peer Data Availability Sampling) is the centerpiece of Fusaka and arguably the most important innovation for Ethereum’s scaling roadmap. It’s formalized in EIP-7594 and represents a fundamental shift in how the Ethereum network verifies data availability.

The Problem Before PeerDAS

Since Dencun (March 2024), Ethereum introduced “blobs” to store data more cheaply than calldata. However, every node on the network still needed to download and verify all blob data. This created a significant bottleneck:

• High bandwidth requirements for running a node
• Expensive hardware to store and process blob data
• Network throughput limited by the weakest node operators
• Limited ability to increase blob space without centralizing the network

How PeerDAS Works

PeerDAS fundamentally changes this model. Instead of every node downloading all blob data, nodes now:

1. Sample Small Pieces: Each node randomly samples only a small portion (typically 1–2%) of blob data from each block.
2. Verify Collaboratively: Nodes collectively verify that all data is available by sharing their sample results with peers.
3. Cryptographic Confidence: Mathematical guarantees ensure that if even one node can sample a piece successfully, all data must be available to the network.
4. Drastically Reduce Load: Bandwidth and storage requirements drop dramatically, enabling orders of magnitude more data throughput.

PeerDAS is not full danksharding (which targets 1 MB blocks of data availability), but it is the critical stepping stone. It proves the concept works at scale and prepares the network for the final danksharding roadmap.

3. Other Notable EIPs in Fusaka

While PeerDAS is the headliner, Fusaka includes 12 EIPs total. Here are the other significant ones:

EIP-7825: Transaction Gas Limit Cap

EIP-7825 introduces a 16.78 million gas cap per transaction. This prevents pathologically large transactions from monopolizing block space and adds predictability to gas consumption patterns. It’s a safety mechanism to protect network stability as block sizes and complexity continue to grow.

Block Gas Limit Changes

The default block gas limit targeting increases, moving toward 60 million gas per block. This gradual increase in throughput, combined with PeerDAS, significantly amplifies Layer 2 scaling benefits. More gas per block means more transactions can be processed and settled on Ethereum mainnet.

These upgrades work in concert to improve network efficiency, reduce costs, enhance security, and prepare Ethereum for the next generation of scaling. Each EIP has been rigorously tested and reviewed by the research and development community.

4. Impact on Layer 2 Users

The primary beneficiary of Fusaka is the Layer 2 ecosystem. Optimistic and ZK rollups post transaction data to Ethereum (the “Calldata” or “Blob” cost), and Fusaka directly reduces this cost through increased data availability capacity.

Direct Cost Reductions

With PeerDAS and the increase in block gas limits, Layer 2 solutions can post data more cheaply. This translates directly to lower transaction fees for end users. For context:

• Dencun (March 2024) reduced L2 fees by 50–90% through blobs
• Fusaka (December 2025) further reduces fees by enabling PeerDAS and higher throughput
• Future upgrades will continue this cost reduction trajectory

Improved User Experience

Lower fees enable more use cases on Layer 2:

• Smaller transactions become economically viable
• Gaming and NFT applications see better economics
• Micropayment and subscription models become practical
• Developing-world users benefit from sub-cent transaction costs

For Layer 2 users, Fusaka represents tangible fee reductions immediately and sets the stage for even cheaper transactions in the future. Combined with Glamsterdam’s MEV transparency improvements, Layer 2 becomes increasingly competitive with centralized payment systems.

5. Impact on Node Operators

Fusaka fundamentally improves the economics and hardware requirements for running Ethereum nodes, promoting decentralization and network resilience.

Reduced Hardware Requirements

Before PeerDAS, the bandwidth and storage needed to run a full node increased with every blob addition. PeerDAS decouples node hardware requirements from network throughput:

• Lower bandwidth: Only sample pieces instead of all data
• Lower storage: No need to store full historical blob data
• Cheaper to operate: Standard computers can run nodes without specialized hardware
• More decentralization: Lower barriers to entry encourage participation

Validator Economics Unchanged

For Ethereum stakers and validators, Fusaka doesn’t significantly change economics. Staking rewards remain determined by network participation. However, improved data availability increases the utility and value of the network, indirectly supporting long-term validator economics.

Increased Network Participation

By reducing the cost of node operation, Fusaka encourages more individuals and organizations to run nodes, strengthening network decentralization and censorship resistance.

The net effect is that Fusaka makes Ethereum more accessible to everyday participants, strengthening the network’s true decentralization rather than consolidating power among large operators.

6. What’s Changed Since Fusaka Launched

Since Fusaka went live on December 3, 2025, the Ethereum ecosystem has seen rapid adaptation and maturation of PeerDAS support across nodes, clients, and applications.

Network Statistics

The upgrade rolled out smoothly without consensus issues. Participation from validators has been strong, and the network has operated stably through PeerDAS’s new data availability sampling protocol.

Layer 2 Adoption

Layer 2 solutions have quickly benefited:

• Major rollups (Arbitrum, Optimism, Starknet, zkSync) optimized for PeerDAS
• Transaction fees on L2 decreased by 20–40% relative to pre-Fusaka levels
• Increased throughput enabled new applications in gaming, DeFi, and social
• User onboarding accelerated due to lower economic barriers

Node Implementation Updates

Ethereum clients (Prysm, Lighthouse, Lodestar, Teku, Nimbus) and execution clients (Geth, Erigon, Besu, Nethermind) all released updates to support PeerDAS. Home stakers and node operators worldwide upgraded smoothly.

The transition to Fusaka has reinforced Ethereum’s position as the leading platform for decentralized applications and Layer 2 scaling. The upgrade is already delivering on its promises of increased throughput and reduced costs.

7. Glamsterdam: The Next Frontier

With Fusaka successfully live, Ethereum research and development is focused on the next major upgrade: Glamsterdam, expected in 2026. While Fusaka emphasized scaling through data availability, Glamsterdam focuses on user experience, censorship resistance, and MEV (Maximal Extractable Value) transparency.

Glamsterdam’s Focus Areas

Censorship Resistance

Glamsterdam will improve mechanisms to ensure that transactions cannot be arbitrarily censored, even by powerful validators or relayers. This aligns with Ethereum’s core values of decentralization and permissionless access.

MEV Transparency & Mitigation

Maximal Extractable Value (MEV) is the profit that validators can extract by reordering transactions. Glamsterdam aims to make MEV more transparent and reduce its negative effects on users, improving fairness in the protocol.

User Experience Improvements

Glamsterdam will enhance the experience for end users and developers, potentially through improved tooling, better fee prediction, and more efficient transaction handling.

Timeline & Expectations

While no formal date has been announced, the Ethereum community expects Glamsterdam to reach mainnet sometime in 2026. Like Fusaka, it will undergo multiple testnet phases before mainnet launch. The upgrade is currently in research and specification phases.

For users and developers, Glamsterdam promises further cost reductions (through improved MEV handling), better censorship resistance, and a smoother overall experience. Combined with Fusaka’s throughput gains, 2026 will see Ethereum delivering unprecedented scaling and fairness to users worldwide.

8. The Path to Full Danksharding

PeerDAS is a critical stepping stone toward Ethereum’s ultimate scaling solution: full danksharding. Understanding the roadmap helps clarify where Ethereum is heading long-term.

What is Danksharding?

Danksharding, named after Ethereum researcher Dankrad Feist, is a fundamental redesign of how Ethereum stores and verifies data. Instead of every node storing all data, danksharding uses 2D-Reed-Solomon erasure codes to allow nodes to store only a fraction of data while still being able to verify everything.

Full Danksharding Target: 1 MB Blocks

The endpoint of this roadmap is blocks of approximately 1 MB of data availability per block, compared to the current ~128 KB. This represents an 8x increase in throughput at the protocol level. For Layer 2 users, this translates to even cheaper transactions than Fusaka enables.

The Roadmap: Step-by-Step

Here’s how Ethereum gets from PeerDAS to full danksharding:

1. Blobs (Dencun, March 2024): Introduced simple blob data structure for Layer 2 to use.
2. PeerDAS (Fusaka, Dec 2025): Enable data availability sampling, proving the concept works at scale.
3. Full Danksharding (Post-Glamsterdam): Implement complete 2D-Reed-Solomon codes and erasure codes, targeting 1 MB blocks.
4. Full Rollup Maturity: Layer 2 solutions reach their absolute theoretical throughput potential, supporting billions of transactions per day.

For Ethereum users and developers, the danksharding roadmap is unambiguously positive. Every step makes the network cheaper, faster, and more scalable. Fusaka is the proof that this works. The remaining steps will deliver on Ethereum’s ultimate vision of a globally accessible, self-sovereign financial layer.

9. Frequently Asked Questions