TL;DR

Soundness Layer is a decentralized verification layer designed to solve the scalability and cost challenges of on-chain data validity, more specially Zero-Knowledge Proof (ZKP) verification. By leveraging parallel execution, Move's secure smart contracts, and Walrus's decentralized storage, Soundness Layer offers fast finality, censorship resistance, and cross-chain interoperability. It significantly reduces on-chain verification costs, making ZKP-based applications like zk-Rollups, zkBridges, and zkApps more affordable and scalable.

🦭Walrus, a decentralized storage network, plays a key role by ensuring verifiable data is stored efficiently and can be reconstructed even if some nodes fail. When combined with Soundness Layer, Walrus enables cost-effective validity checks, reducing the on-chain costs of attestation. Together, they create a robust infrastructure for scalable, decentralized, and affordable proof verification, paving the way for broader adoption of ZKP-based technologies.

This combination of low latency, high throughput, and censorship resistance makes Soundness Layer a foundational building block for the next generation of dApps.

Soundness Layer: A Scalable Verification Layer with Fast Finality

In a world where trust is often hard to come by, verifiable computations are becoming increasingly crucial. Whether it’s ensuring the integrity of financial transactions, validating the results of complex algorithms, or proving the authenticity of digital identities, the ability to verify computations without revealing sensitive data is a cornerstone of modern cryptography. Zero-Knowledge Proofs (ZKPs) have emerged as a powerful tool to achieve this, allowing one party to prove to another that a statement is true without disclosing any underlying information. This capability is not just a theoretical marvel—it’s a practical solution to some of the most pressing challenges in blockchain and beyond.

Zero-Knowledge Proofs (ZKPs) have become a game-changer in the blockchain space, offering solutions for privacy, scalability, and cost efficiency. From zk-Rollups to zkApps, ZKPs are transforming how we think about blockchain applications. However, as the demand for ZKP-based solutions grows, so do the challenges, particularly around on-chain verification costs and scalability.

Current solutions, like Proof Aggregation Techniques (PATs) and dedicated zk Verification Layers (VLs), have their own limitations. PATs often rely on centralized systems, which can lead to censorship and liveness issues. On the other hand, VLs claim to push decentralization forward, but here’s the catch: many still quietly depend on centralized sequencers and centralized DA or outsource critical tasks (like signature aggregation) to a single trusted node. Of course, they might reduce costs or improve scalability, but this hybrid approach often means trading true decentralization for convenience. This leaves a gap in the market for a solution that combines decentralization, speed, and scalability.

Soundness Layer, a fully decentralized verification layer designed to tackle these challenges head-on. By leveraging cutting-edge technologies like Sui's parallel execution, Move's secure smart contract environment, and Walrus's optimized data availability, Soundness Layer offers a censorship-resistant, high-throughput solution with fast finality. In this blog post, we’ll break down what Soundness Layer is, why it matters, and how it can revolutionize the blockchain ecosystem.

The Problem: On-Chain Verification Costs and Scalability

Blockchains like Ethereum, while powerful, are not optimized for heavy cryptographic computations. Verifying zero-knowledge (ZK) proofs on-chain remains an expensive and time-consuming process, limiting the scalability of applications that rely on them. For instance, Ethereum can only verify up to 120 ZK proofs per block due to gas constraints. As the market for ZK proofs is projected to grow to $10 billion by 2030, this bottleneck becomes increasingly problematic.

So far, the total gas fees spent on Ethereum L1 for ZK proof verification have reached a staggering $61,392,366 as of March 2025, according to this Dune dashboard created by Nebra and OurNetwork.

The Evolution of ZK Proof Costs

The graph below tracks total settlement fees paid by ZKP projects on Ethereum L1 from January 2022 to March 2025. While cumulative costs have surged past $40 million, recent months show a decline in expenses thanks to innovations like proof aggregation and dedicated ZK verification layers.

ZKP L1 cost, source: https://dune.com/queries/3919405

Projects such as Scroll and RiscZero are significantly reducing gas fees by batching multiple proofs into a single transaction, minimizing the on-chain verification burden. Meanwhile, zk infrastructure layers like Succinct and =nil; Foundation are streamlining proof processing, decoupling heavy computation from L1 execution. These optimizations are reflected in the graph’s flattening trend post-mid-2023, signaling that the ecosystem is addressing scalability while maintaining security. As ZK adoption continues to grow, these innovations are critical for keeping costs sustainable for all zkApps.

The Latency-Cost Tradeoff

While current techniques provide cost-effective solutions for zkApps where settlement speed isn’t a major barrier, real-time applications remain a challenge. The speed vs. cost tradeoff still presents a major roadblock for instant-settlement zkApps—think gaming, prediction markets, or high-frequency DeFi trades.

Number of active ZKP user, source: https://dune.com/queries/3986388/6708479

The following snapshot illustrates the growing importance of ZKPs in blockchain, showcasing their role in building trust and efficiency in decentralized systems. As adoption accelerates, this trend is only set to grow.

L1 spend over time per project, source: https://dune.com/queries/3891266

Currently, the ZKP space is largely dominated by scalability-focused applications like zkRollups, zkBridges, etc. These projects thrive because their use cases—batch transactions, cross-chain bridging, etc.—do not require instant finality. However, for applications that demand both rapid settlement and low on-chain costs, the landscape remains underdeveloped.

Real-time DeFi trades, gaming, and prediction markets require instant proofs and cheap fees. Yet today’s ZK infrastructure forces developers to make a tradeoff:

While many scalability solutions reduce costs by batching proofs over hours, this approach doesn’t work for applications that need instant finality. As a result, zkApps that require both speed and low fees—like real-time DeFi trades or gaming—are still missing from the ecosystem. Until ZK infrastructure improves, this gap remains largely unfilled.

Expanding the Use Cases for Verifiable Computation

Beyond ZK proof verification, Soundness Layer is expanding its scope to broader data verification challenges. One key area we are currently working on is verifiable AI dataset storage, ensuring that stored data remains tamper-proof and publicly verifiable. Additionally, we are exploring applications in verifiable KYC data, which could enhance user onboarding experiences while preserving privacy.

As the ecosystem matures, the need for efficient, low-cost, and real-time verifiable computation will only increase. The next wave of ZK innovation is not just about reducing costs—it’s about unlocking new possibilities for decentralized applications.

Introducing Soundness Layer

Soundness Layer is a decentralized verification layer that addresses these challenges by offering:

• Fast Finality: Proofs are verified and finalized in a few seconds, enabling high-throughput applications.

• Censorship Resistance: No single entity can control or suppress proofs, ensuring a fair and open system.

• Shared Economic Security: Validators can re-stake their assets across multiple blockchains, enhancing decentralization and security.

• Cross-Chain Interoperability: Proofs can be efficiently verified across different blockchains, thanks to a decentralized data availability layer.

Key Features of Soundness Layer

1. Highly Decentralized: Soundness Layer ensures that no single entity can control the verification process. Validators are well-incentivized, and the verification logic is transparent and auditable.

2. Censorship-Resistance: The system is designed to prevent malicious actors from excluding or reordering proofs, safeguarding against bribery attacks.

3. Shared Economic Security: By allowing validators to re-stake their assets across multiple blockchains, Soundness Layer enhances the overall security and decentralization of the network.

4. Low Latency: Proofs are verified and finalized in a few seconds, making it ideal for applications that require high throughput and fast finality.

5. Decentralized Data Availability: Proofs are stored on Walrus as a cost-effective decentralized data availability layer, and the attestations are stored on Sui; ensuring that they remain accessible and verifiable across different chains.

How Soundness Layer Works

Soundness Layer uses Sui as the main coordinator, which allows for parallel processing of transactions. This significantly improves scalability and throughput compared to traditional blockchain systems. Combining it with Walrus gives us a solid foundation for how proofs are stored and delivered to our validators.

Here’s a high-level overview of how it works:

1. Proof Storage: zkApps like zkVMs, zk-Rollups, zkBridges, and zkML submit their proofs to Walrus, as a cost-effective decentralized data storage. Walrus can enable efficient proof of availability for free.

2. Proof Submission: Once the data is stored on Walrus the users can submit their requests to Soundness Layer by calling new_proof function in our Move smart contract. This call is super cheap since the users dont need to store proofs on-chain —they only need to submit their blob ID.

3. Sequencing: Fair sequencing is crucial to ensure that proofs are processed in the correct order, preventing manipulation and maintaining the integrity of the system. In many decentralized environments, improper sequencing can lead to unfair advantages, delayed processing, or even security vulnerabilities. Instead of building a separate sequencing mechanism from scratch, we take advantage of Sui’s built-in sequencing capabilities, which handle ordering efficiently. This allows us to focus on proof verification while benefiting from Sui’s infrastructure for free. On top of that, our re-staking mechanism adds an extra layer of economic security, further reinforcing the trustworthiness of the network.

4. Data fetching: Since the proofs are stored on Walrus, validators can fetch the data simply by accessing their blob IDs. Using Walrus as the backbone of the Soundness Layer helps us cut costs by avoiding redundant uploads and reusing shared data across multiple proofs.

5. Verification: Validators verify the proofs using a native verifier code while retrieving data from Walrus. This process is proof-agnostic, meaning it can support a wide range of proof systems without requiring changes to the consensus mechanism.

6. Attestation: The Soundness validators confirm the validity of the proofs by signing the data details and then calling transfer_prove function in our Move smart contract to provide their shares. We don’t need a centralized node to batch the partial signatures since we use a consensus-less mechanism, improving scalability and throughput. We provide more details on this soon.

7. Fast Light Client & Blockchain Interoperability: The batched signatures are now on the Sui blockchain. We can fetch them and attest them to the parent chain. To ensure the authenticity of the claimed data from Sui, we rely on Sui (zk) light client that efficiently verifies the correctness of block headers and other data, enabling seamless cross-chain interoperability. Instead of a zk light client, we could consider Ika. It’s designed for sub-second MPC, handling up to 10,000 TPS with hundreds of signer nodes, all without relying on trust. Once it's ready, it could be a strong option for multi-chain coordination on Sui. Check it out here: ika.xyz. The verified proofs are attested to parent chains like Ethereum, ensuring that they are recognized and accepted across different blockchains.

🦭 Why Walrus is Important?

Walrus, as a decentralized storage network, plays a crucial role in enabling scalable and cost-effective data availability for blockchain applications and uses Sui as its coordinator layer too. By leveraging advanced erasure coding technology like Red Stuff, Walrus ensures that data is stored efficiently and can be reconstructed even if a significant portion of storage nodes fail. This high level of fault tolerance and decentralization makes Walrus an ideal solution for storing verifiable data, such as zkApps, which are essential for applications like zkML, zk-Rollups, zkBridges, and other zkApps.

When combined with Soundness Layer, the verifiable data stored on Walrus can be efficiently checked for validity at a low cost. Soundness Layer’s decentralized verification process, powered by its DAG-based consensus and re-staking mechanism, ensures that proofs are verified quickly and securely. This synergy between Walrus and Soundness Layer significantly reduces the on-chain costs of attestation, making it a cost-effective solution for applications that require high throughput and fast finality. Together, they create a robust infrastructure for scalable, decentralized, and affordable proof verification, paving the way for broader adoption of ZKP-based technologies.

🧭 Real-World Applications

A potential application for Soundness Layer can be a tool similar to zkLogin but compatible with Ethereum transactions. zkLogin, deployed on Sui as one of the widely used zkApps to date with over 7 million transactions to date, is a powerful tool that allows users to log into Sui wallets using their existing Web2 credentials (like Google, Twitch, GitHub, …). Traditionally, creating a wallet requires users to remember complex passwords and store recovery phrases, which can be a barrier to entry for many. With a similar idea to zkLogin for Ethereum transactions, users can generate an ephemeral key pair and prove their identity using ZK proofs, all while keeping their credentials private.

Soundness Layer can be seen as a complementary part of this tool to significantly reduce the on-chain costs of verifying these proofs, making it a more user-friendly and cost-effective solution while keeping everything decentralized. This is just one example of how Soundness Layer can simplify the onboarding process and drive broader adoption of Web3 technologies. In general, Soundness Layer stands out from other verification solutions by being fully decentralized in sequencing, attestation, and data storage. These key properties make it a strong foundation for the next generation of zkApps.

Soundness Layer Testnet: Join now our upcoming testnet!

Want to verify a ZK proof without waiting for slow, expensive on-chain settlement? The Soundness Layer lets users submit proofs to be verified on Walrus through our network of nodes while using Sui as the main coordination layer. To make things easier for you, you don’t need to worry about installing all the dependencies—you can simply interact with our server instead which is going to be live soon!

1️⃣ Setup: Install the Soundness CLI & Generate Keys

Before submitting proofs to our server, install the Soundness CLI and create a key pair for authentication. Make sure you have Rust and Cargo installed, as well as the necessary dependencies for building Rust projects before running this code. For more details please refer to the repo: https://github.com/SoundnessLabs/soundness-layer

Quick Installation

Install the CLI with a single command:

After installation, restart your terminal or run:

source ~/.bashrc  # for bash
# or
source ~/.zshenv  # for zsh

Then you can use the CLI:

soundnessup install  # Install the CLI
soundnessup update   # Update to the latest version

Manual Installation

If you prefer to install manually, you can use Cargo:

Clone the Soundness Layer repository:

git

Navigate to the folder:

cd

Install the Soundness CLI:

cargo install --path

Usage

Generate a Key Pair

soundness-cli generate-key --name

This will generate an Ed25519 key pair and stores the key locally in key_store.json file. Here is an example output:

  ✅ Generated new key pair 'my-key'
  🔑 Public key: <base64-encoded-public-key>

You can see the list of your public keys by running the following command:

Exporting Key Mnemonic

To export the mnemonic phrase for a stored key pair:

soundness-cli export-key --name my-key

⚠️ Warning: Keep your mnemonic phrase secure and never share it with anyone. Anyone with your mnemonic can access your key pair.

Get Whitelisted for the Testnet

To interact with the Soundness Layer server, you need to be whitelisted. Follow these steps:

1. Follow us on X

2. Join our Discord

3. Send your public key in the #testnet-access channel using this command format:

   !access <base64-encoded-public-key>

4. Wait for approval—we’ll add your key to the whitelist promptly.

Once approved, you can start submitting proofs by interacting with our server which is going to be live soon! 🎉

The full code for the Soundness Layer—including the verification server and client SDK—will be open-sourced in Q2 2025. Builders, get ready to fork, tweak, and deploy your own version!

Conclusion

Soundness Layer is a powerful solution to the scalability and cost challenges facing ZKP-based applications. By offering fast finality, censorship resistance, and cross-chain interoperability, it provides a robust foundation for the next generation of zkApps. Whether you’re building a private voting system, a gaming platform, or a decentralized identity solution, Soundness Layer can help you achieve your goals more efficiently and cost-effectively.

What’s Next?

We will annouce our testnet soon and the whitelisted users can interact with our server.

Also, in our upcoming whitepaper, we will dive deeper into the economic security aspects of Soundness Layer, explore the performance metrics of the system, and discuss how our design choices impact the broader blockchain ecosystem. Stay tuned for more updates!

Soundness Layer is paving the way for a Sound Internet. Join us as we build the future of zkApps!

Useful Resources:

https://docs.walrus.site/walrus.pdf

https://www.ournetwork.xyz/p/on-261-zoomed-in-on-zero-knowledge-proofs

http://x.com/EmanAbio/status/1848785669700915623