South Korean super app Toss partners with Optimism for won linked stablecoin trial

South Korean financial super-app Toss has signed a strategic agreement with Optimism and Sunnyside Labs to test blockchain infrastructure for South Korean won-linked stablecoins through a three-month technology verification program.

According to a press release shared with crypto.news, the financial technology company will work with Ethereum layer 2 network Optimism and privacy technology developer Sunnyside Labs to examine whether blockchain infrastructure can support institutional payment systems while meeting financial regulations in South Korea. The companies will carry out a proof-of-concept (PoC) over the next three months.

Three areas under review

As part of the project, the companies will evaluate whether financial institutions can directly manage payment and settlement processes, comply with customer identification and anti-money laundering requirements, and protect sensitive transaction information while operating on a public blockchain.

Those requirements form the basis of the technical assessment, with Optimism providing blockchain infrastructure through its OP Stack technology while Sunnyside Labs, one of the network’s core developers, will integrate its Privacy Boost solution to address confidentiality concerns.

Privacy Boost is designed to solve one of the key limitations of public blockchains, where transaction details and wallet balances are generally visible to network participants. According to the companies, the technology allows sensitive financial data to remain private while still enabling regulated institutions to verify transactions and maintain existing compliance standards.

The companies also said the system is built to support high transaction volumes, making it suitable for payment services that process large numbers of users simultaneously.

Toss, which serves around 30 million users and supports more than 500,000 online and offline merchants, plans to gradually expand blockchain-based experiments across its payment and platform services. 

A Toss official said the project is intended to verify infrastructure that combines Ethereum’s security with a dedicated network built for local currency-based financial services while allowing interoperability with other blockchain ecosystems.

OP Stack selected for infrastructure testing

At the center of the verification is OP Stack, Optimism’s modular blockchain framework that supports dedicated application-specific chains while relying on Ethereum for security and settlement. Layer 2 networks process transactions separately from Ethereum before finalising them on the main chain, helping reduce costs and improve transaction speeds.

According to Toss, the companies will examine whether OP Stack can support a blockchain-based financial network tailored for Korean digital payment services instead of relying on shared public infrastructure.

Optimism’s technology is already used by more than 30 blockchain networks, including projects developed by Sony, World Chain, Uniswap, OKX Layer, and Kraken. The company also offers institutional deployments designed to satisfy regulatory and security requirements, with regulated financial firms such as Europe’s Bitpanda already adopting the technology.

The collaboration comes weeks after Optimism completed a 4-week experiment on its OP mainnet that tested stake-based transaction ordering alongside its existing gas-fee system. The pilot explored whether staking incentives could improve transaction prioritisation without changing the experience for regular users, adding to the network’s ongoing work on blockchain infrastructure.