Toss, the fintech super-app with more than 15 million users in South Korea, has signed a memorandum of understanding with Optimism and Sunnyside Labs to run a proof of concept on a Korean won-pegged stablecoin. The three-month PoC will test whether Optimism’s layer-2 infrastructure can support compliant digital currency payments in one of Asia’s most tightly regulated financial markets.

What the partnership actually involves

The MOU, signed on July 8, pairs three organizations with very different skill sets. Toss brings the user base and financial services muscle. Optimism contributes its OP Stack, the modular framework that powers its Ethereum layer-2 network. Sunnyside Labs rounds out the trio with privacy-focused solutions, a critical piece of infrastructure when you’re dealing with regulated payments in a country that takes KYC and AML seriously.

Kyu-ha Kim, Toss’s Chief Business Officer, emphasized the importance of the collaboration in understanding the feasibility of a KRW-pegged stablecoin. The PoC will specifically assess whether the OP Stack can handle the throughput, compliance, and cost requirements that a payment-grade stablecoin demands.

Back in March 2026, the company announced plans to issue a won-backed stablecoin. Then in June, Toss Bank signed a separate MOU with the Solana Foundation to test stablecoin-based remittance and settlement. The Optimism track focuses on layer-2 Ethereum infrastructure. The Solana track focuses on remittance use cases.

Why South Korea matters for stablecoins

That’s precisely why Toss is running a PoC rather than going straight to market. The company operates Toss Bank, a fully licensed digital bank, alongside its payments super-app. A stablecoin that gets shut down would be a reputational catastrophe for a platform that has spent years building trust with Korean consumers.

The risk, of course, is execution. Three months is a short window for a PoC, and the gap between “technically feasible” and “regulatorily approved” can be measured in years in South Korea. No regulatory approvals have been granted, and no specific token issuance details have been disclosed. The PoC could conclude that the technology works perfectly and still sit in regulatory limbo for an extended period.