A soulbound token (SBT) is commonly a non-fungible token whose transfer rules bind it to an account. Instead of functioning as a freely traded collectible, it can represent a membership, achievement, or credential associated with that account. Its meaning comes from the issuer and application, not simply from being recorded on a blockchain.
Restrictions are implemented in code
Soulbound designs are not all identical. ERC-5192 provides an interface for detecting whether an NFT is locked; ordinary ERC-721 transfers must fail while it is locked. ERC-5484 specifies non-transferable tokens with recipient consent and predetermined rules about who may burn them.
Revocation, expiration, unlocking, or replacement therefore depend on the chosen design. Some systems can support account changes through authorized burning and reissuance. The label alone does not promise automatic recovery after a key is lost.
A token is not proof of a person
An application must assess who issued the token and what evidence supports its claim. Preventing token transfers does not by itself prove a unique human identity or prevent the account’s controller from changing.
Publicly visible credentials can also expose relationships or sensitive attributes. Consent, data minimization, and correction mechanisms matter. Non-transferability does not guarantee privacy, trustworthy credentials, or financial value.