ERC-3643

ERC-3643 is an Ethereum token standard for permissioned security tokens - tokens that can only be held and transferred by investors who have been verified. Also known as the T-REX standard, it was built specifically for regulated real-world assets, where the issuer must control who owns the token at all times. It is a finalized ERC, maintained by an industry association.

Its defining feature is on-chain identity. Every potential holder is linked to a verified identity (using the ONCHAINID framework), and the token contract checks that identity against a set of compliance rules before any transfer executes. If a buyer is not verified, not on the approved list, or barred by a rule - a jurisdiction block, a holding limit, a lock-up period - the transfer simply reverts. Compliance is enforced by the code, not by a back-office promise.

ERC-3643 extends the ERC-20 model, so balances and transfers look familiar to standard tooling, but it adds the identity registry, the compliance module, and agent roles that let the issuer freeze accounts, force transfers for legal recovery, or recover tokens from a lost wallet. In practice it combines a whitelist with pluggable transfer restrictions.

This matters because a security cannot behave like a permissionless token. A token entitling you to someone's profits usually must stay within a pool of KYC'd, eligible investors, and ERC-3643 bakes that requirement into the asset itself, so it travels with the token across wallets and venues.

The alternative lineage is ERC-1400, an earlier security-token suite. ERC-3643's emphasis on built-in verified identity has made it a common choice for compliant issuance as of 2026.

Source: ERC-3643 Association (erc3643.org), as of 2026.