PLC is a persistent global identifier system, which allows accounts to retain relationships while changing names or migrating between service providers. It makes use of cryptography and gives individuals (or organizations) direct control and ownership over their identitifier, but does not make use of any blockchain or cryptocurrency technology, and is inexpensive enough to provide as a no-cost service.
PLC is a method which implements the W3C Decentralized Identifier (DID) standard. This means it is interoperable and reusable by other applications and organization.
Bluesky PBC developed DID PLC when designing the AT Protocol (atproto) because we were not satisfied with any of the existing DID methods. We wanted a strongly consistent, highly available, recoverable, and cryptographically secure method with fast and cheap propagation of updates.
PLC stands for "Public Ledger of Credentials". The system has been in production use for several years, with over twelve million registered DIDs in the atproto network as of October 2024. We feel that the existing system provides value and is worth consideration as a persistent identifier for other applications. The system may evolve to add functionality or improve security, but will do so in a backwards-compatible manner so that existing DIDs will continue to resolve.
DID resolution can be as simple as:
curl -s "https://plc.directory/did:plc:ewvi7nxzyoun6zhxrhs64oiz" | jq .Jump in to the specification to understand how to verify self-certifying operation logs.
Check out the HTTP API documentation (generated from an OpenAPI schema) for details on how to submit operations, fetch the current DID document, or get a paginated export of all operations for all accounts.