Solid Protocol

Solid (short for Social Linked Data) is a specification for separating your personal data from the applications that use it. On the web most people use today, your data lives wherever the app vendor decided to put it, your photos in one company's database, your contacts in another's, your medical history in a third's, and moving between apps usually means starting over, or hoping there's an export button. Solid inverts that: you store your data in a personal data store called a Pod (see: Pod), you decide which apps and people can read or write to specific parts of it, and applications become interchangeable, each one asks your Pod for permission, rather than owning a copy of your data itself.

The protocol was designed by Tim Berners-Lee, the same person who invented the Web and later chaired the W3C for decades, starting around 2015 at MIT, and is developed today through Inrupt (the company he co-founded to build it commercially) and the open W3C Solid Community Group, which publishes the actual technical specifications. Solid is not a lab project: the BBC, the UK's NHS, and the Flanders regional government in Belgium have all run real Solid deployments or pilots, well outside the standards-community bubble.

Solid is built from several separable pieces, each with its own entry in this Lexicon: WebID for identity, LDP for the read/write mechanics, WAC/ACL for authorization, and RDF/Turtle for how the data itself is represented.

Where Solidus stands

Solidus did not build Solid, does not extend it, and is the junior party in this relationship, not a co-author. Our Pod product is Solid-compatible and migration-ready, meaning data can move to and from a real Solid pod without much friction, but it is not Solid-conformant and does not run the Solid Protocol. Today it is Community Solid Server (a real, independently-built Solid implementation) plus a did:solidus identity bridge, backed by JWT+Postgres with WAC-style access rules layered on top. Getting to full protocol conformance is real, undone engineering work, not a formality we're skipping for time.

The one place we genuinely diverge from Solid, and the only claim worth making about it, is architectural: Solid never adopted W3C DIDs or Verifiable Credentials, WebID identifies you via an HTTP-plus-TLS-certificate address, and its access-control rules govern documents, not verifiable claims. Solidus bets that a chain-anchored DID, with revocation enforced as a consensus rule, is a better fit for that layer. That is a bet we're making, not a result we've proven.

Proof

Read the protocol spec yourself at solidproject.org/TR/protocol. To see it running for real, look at the BBC's, NHS's, and Flanders government's Solid deployments, all built independently of Solidus. We don't offer a proof of our own full conformance, because we don't have full conformance.