South Korean fintech company Toss has signed an agreement with Ethereum Layer 2 network Optimism and privacy technology developer Sunnyside Labs to test blockchain infrastructure that could support a won-linked stablecoin.
The three companies will run a three-month proof-of-concept (PoC) to examine whether Optimism’s OP Stack can be used for blockchain-based financial services in South Korea. The project will also test whether financial institutions can meet customer verification, anti-money laundering, and privacy requirements while using a public blockchain.
Toss (Viva Republica) is running a 3-month PoC with Optimism and Sunnyside Labs to explore building KRW stablecoin infrastructure on Optimism’s OP Stack. The MOU covers testing whether a financial institution can directly manage settlement, meet KYC/AML requirements, and protect… pic.twitter.com/zTieLhY2SR
— Tony Chung (@jayc_BM) July 8, 2026
Toss said the goal is to determine whether blockchain can support regulated payment and settlement systems without compromising security or customer data.
Privacy will be tested alongside blockchain performance
The PoC will focus on three areas, which are giving financial institutions direct control over payment and settlement, meeting KYC and AML rules, and protecting transaction data on public blockchain networks.
Optimism will provide the blockchain infrastructure through its OP Stack, while Sunnyside Labs will supply its Privacy Boost technology. The privacy tool is designed to prevent sensitive transaction data from being publicly exposed while still allowing financial institutions to access the information they need for compliance.
Toss said this approach could allow blockchain-based financial services to operate under standards already required in the banking sector.
Public blockchains are becoming private enough for banks
For years, one of the biggest barriers to using public blockchains in finance has been transparency. Every transaction can usually be viewed by anyone, making it difficult for banks and payment companies to use the technology for customer accounts.
Several projects are now trying to solve that problem. JPMorgan has developed blockchain payment systems with restricted access for institutional clients, while Canton Network was built to let financial firms share blockchain infrastructure without exposing sensitive transaction data. Privacy tools are also becoming part of public blockchain ecosystems instead of relying only on private networks.
Rather than creating a private blockchain, the company is testing whether Ethereum’s security can be combined with privacy technology that meets financial regulations. If the trial succeeds, it could provide a model for stablecoin payments that work on public blockchain infrastructure while meeting the standards expected by banks and financial regulators.
Toss Bank signed a memorandum of understanding with the Solana Foundation to examine blockchain-powered remittance and settlement services, an important step in the growing convergence of traditional banking and crypto infrastructure.
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