OP Stack layer 2 (X Layer)

X Layer is a layer 2 built by OKX, whose public mainnet opened on 16 April 2024. It launched as a zero-knowledge chain on Polygon's CDK that kept its transaction data with a committee rather than on Ethereum, and by December 2025 OKX had moved it to Optimism's OP Stack. L2BEAT now records it posting its transaction data to Ethereum, but lists it among 'Others' rather than rollups, because fewer than five outside parties can challenge its state, and notes that its contracts can be upgraded with no delay. Fees are paid in OKX's own token, OKB, not in ETH. Also: Optimism, post of 9 December 2025