Cardano node's evolution towards diversity and modular design

As the Cardano ecosystem matures in 2025 and beyond, improving the core node software is one of several priorities for strengthening the network infrastructure. Introducing multiple, diverse node implementations – built by different teams and in different programming languages – can improve network resilience, reduce systemic risk, and better reflect the principles of decentralization.

Why node diversity matters

Imagine a complex system where everyone relies on a single tool. If that tool has a bug or a performance issue, the entire system is compromised. Multiple node variants would mean that if one implementation fails or becomes adversarial, others can continue to operate, enhancing the network's overall stability and security.

This isn't just about preventing single points of failure; it's also about innovation. Different teams can optimize nodes for various use cases, platforms, and performance profiles, fostering a healthier, more adaptable ecosystem.

Key planned improvements for the Cardano node

Input | Output (IO) has proposed several improvements for the Cardano node to enhance its stability, reduce operational costs for stake pool operators (SPOs) and others, and improve scalability. These include:

• Log-structured merge (LSM) trees. This is a memory management upgrade designed to reduce the memory required to run a node. By moving data structures like the UTXO set onto disk, LSM will allow Cardano to scale to potentially billions of users and significantly larger UTXO sets while enabling nodes to run on optimized hardware. This is planned in phases, starting with moving the UTXO set on-disk using Lightning Memory-Mapped Database (LMDB), followed by migrating to a custom LSM library, and finally identifying other ledger state components to migrate.
• Revised stake pool incentive scheme. Proposals are being explored to adjust the current incentive structure, particularly to provide fairer incentives for smaller, single stake pool operations. The goal is to promote greater diversity among SPOs, making it easier for new pools to join the ecosystem.
• Anti-grinding measures. This initiative focuses on strengthening the Ouroboros consensus layer against grinding attacks (where leaders try to manipulate future leader elections). The aim is to increase the difficulty for attackers while minimizing the impact on honest participants, potentially improving settlement times and finality while maintaining robust defenses. Cryptographic alternatives for calculating the η-nonce and updated recommendations for the security parameter K are being explored.
• Tiered pricing. A tiered pricing model is proposed to address network congestion during peak times and unpredictable transaction delays. This would allow users to choose different transaction channels (standard, priority, or assured) with varying fee levels and block inclusion expectations, improving predictability in timing and costs. 

A more accessible node for users: local node services

A new approach is also being considered for users who want a fully trustless interaction with the Cardano blockchain without relying on third-party API providers. 

The planned local desktop node will function as a lightweight full node connecting directly to mainnet peers. It will include a local indexing service, storing only the data relevant to the user to minimize memory and storage requirements. This will allow users to connect any wallet directly to their local node, ensuring trustless operation and compatibility with wallets that currently rely on data API services by simply changing connection parameters. This development is aligned with efforts to decentralize data API services, with the vision that SPOs – and even individual desktop clients – could potentially act as data providers.

Enabling node diversity through project Acropolis

To truly foster node diversity and accelerate development, a shift in architecture is necessary. While Haskell's strengths in formal methods and safety made it an ideal choice for the original implementation, relying on a single language can make development challenging for those unfamiliar with it and can centralize node development.

Project Acropolis aims to address this by transforming the Cardano node into a modular architecture using Rust modules and message passing, built on the Caryatid framework. This initiative seeks to make the Cardano node highly flexible and easy to integrate into applications, envisioning it as an open, adaptable, and decentralized codebase where the node and application seamlessly merge. This new architecture addresses existing challenges such as difficult integration with current node add-ons like DB Sync or Ogmios, high resource requirements, and the monolithic nature of the node, which centralizes development, introduces key person risk, and complicates horizontal scaling.

The project's short-term goals include developing a data node with open client interfaces to provide useful chain-following data without requiring the full Haskell ledger, and replacing common DB Sync functions with Rust components. This approach supports an improved developer experience, a more accessible ecosystem, potentially lower memory and resource demands, faster synchronization and query times, enhanced scalability, and increased code diversity and flexibility. The roadmap for Acropolis begins with building a data node in Q1-Q2 2025, with plans to add validation and block production to become a full Praos node in Q3-Q4 2025, and to explore future scaling solutions like Leios in 2026.

Recent progress: the node diversity workshop

A node diversity workshop held in Paris in April 2025 brought together participants from organizations including the Cardano Foundation, Harmonic Labs, IO Engineering, Sundae Labs, Tweag, and TxPipe. Over three days, they shared successes and insights and addressed challenges related to new node implementations and testing, including discussions on Amaru, one of a number of projects currently seeking development funding from the Cardano treasury. The workshop was run using the open space technology method and featured approximately 25 sessions, which revolved around conformance testing to ensure consistent behavior across different node implementations, the use of tracing and observability tools, and the need for standardized formats like a canonical ledger state. Participants also explored deterministic systems, knowledge-sharing initiatives like CIPs, and the Cardano Blueprint. The workshop highlighted the importance and benefits of node diversity for solidifying protocols and specifications.

Moving forward and getting involved

The momentum from the workshop is driving concrete action items, including drafting CIPs for explicit governance action deposit returns, cleaning up certificates, and proposing canonical formats. Efforts are underway to formalize API specifications and build tools for testing different node implementations, such as blocktree generators and ‘adversarial nodes.’

The goal is to continue this collaborative effort and ensure knowledge is shared across the multiple teams working on core Cardano components. The Cardano Blueprint is an initiative pushing this idea.

To keep the conversation going, the community can engage in a new node development sub-category on the Cardano Forum, with the workshop report serving as the first step. This category is intended as a permanent, searchable space for ongoing discussion.

Additionally, there are plans to start regular online ‘Show and tell’ sessions to maintain collaboration and allow teams to share their progress and challenges. These sessions are envisioned as quick, high-level sharing opportunities, with more in-depth collaborative work organized separately. 

Developers and users interested in contributing or staying informed are encouraged to participate in these ongoing discussions and initiatives.