Skip to main content

​
Soulbound Token

A Soulbound Token (SBT) is a non-transferable, non-fungible token that is cryptographically linked to a specific ‘soul’ or blockchain account. Unlike standard NFTs that can be freely traded or sold on marketplaces, SBTs are designed to represent unique credentials, social identities, or reputations that cannot be moved. Once issued to a wallet address, the token is permanently bound to that identity, serving as a reliable digital marker for personal achievements, professional certifications, or membership statuses that are intrinsically tied to an individual.

​
Definition

A Soulbound Token (SBT) is a non-transferable, non-fungible token that is cryptographically linked to a specific ‘soul’ or blockchain account. Unlike standard NFTs that can be freely traded or sold on marketplaces, SBTs are designed to represent unique credentials, social identities, or reputations that cannot be moved. Once issued to a wallet address, the token is permanently bound to that identity, serving as a reliable digital marker for personal achievements, professional certifications, or membership statuses that are intrinsically tied to an individual.

​
Simple explanation

Imagine an NFT is like a rare trading card that anyone can buy or sell. A Soulbound Token is more like your college degree or your social security card. It belongs specifically to you and cannot be traded to someone else. Because these tokens are permanently stuck to your digital ‘wallet’ identity, they prove that you personally earned a specific qualification or attended an event, without the risk of someone else just buying the credential from you.

​
Why it matters

SBTs enable a decentralized society by allowing individuals to carry their reputation and verified history across different platforms without reliance on centralized identity providers. This creates a foundation for trust-based systems, such as decentralized lending or governance, where a user’s track record matters more than their wallet balance.

​
How it works

SBTs are implemented using specialized smart contracts that lack the standard ‘transfer’ or ‘approve’ functions found in ERC-721 or ERC-1155 token standards. The contract logic explicitly forbids moving the token to a different address after the initial minting process is completed. Some implementations use a revocation mechanism, allowing the issuer to burn or recover the token if the user’s status or credential changes, while maintaining the non-transferability aspect.

​
Real-world example

The Binance Account Bound (BAB) token is a prominent example of an SBT, used to verify the KYC (Know Your Customer) status of users without requiring them to share sensitive personal documents with every decentralized application.

​
Advantages

  • Enables verifiable decentralized identity
  • Prevents the sale or theft of credentials
  • Supports reputation-based governance models

​
Limitations

  • Lack of portability if a wallet is compromised
  • Limited ecosystem support for non-transferable standards
  • Potential privacy risks associated with permanent identity tags

​
Common misconceptions

  • Many believe SBTs can be traded like normal NFTs, but their core feature is their total inability to be transferred.
  • It is often assumed that SBTs are inherently anonymous, but they are actually used to link a real-world identity to an on-chain address.
Canonical knowledge ID: glossary:soulbound-token