Frax is a decentralised finance protocol that initially launched in 2019 with the first fractional-algorithmic stablecoin, FRAX. The design combined partial collateralisation with algorithmic stabilisation. Alongside FRAX, the protocol introduced Frax Shares (FXS) as the governance token. The ecosystem expanded with other products including frxETH, sfrxETH, and the Fraxtal Layer-2 network.

In 2025, following approval of the Frax North Star Proposal (FIP-428), the original FRAX stablecoin was renamed Legacy Frax Dollar. This change separated the legacy design from newer stablecoin products in the Frax ecosystem, such as frxUSD and sfrxUSD, which are now the primary focus of development.

Legacy Frax Dollar is the renamed version of the original FRAX stablecoin. It maintains its peg to the US dollar and continues to be supported across protocols and integrations where FRAX was already in use. Legacy Frax Dollar can still be minted and redeemed in the same way as the original FRAX, but it is now classified as a legacy product.

The protocol’s development direction has shifted toward frxUSD and its derivatives, which feature enhanced mechanisms for stability and yield. Legacy Frax Dollar remains part of the ecosystem for continuity and backward compatibility, ensuring users and integrations are not disrupted by the rebrand.