Solid

Federated Protocol

Decentralized web protocol enabling users to store data in personal online data stores (Pods) with fine-grained access control, based on Linked Data principles and W3C standards. Adds to existing Web standards to realize a space where individuals maintain autonomy, control their data and privacy, and choose applications and services to fulfill their needs. Data storage, entity authentication, access control, and application provider are all loosely coupled

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Details

License MIT License (specifications and reference implementations)
Dev Status 🟢 Active
Dev Status Detail Released (W3C CG specifications published; LWS Working Group producing W3C Recommendations with 'same level of authority as HTML, CSS and Verifiable Credentials'; active development; Dutch Data Vault Foundation deploying personal data vaults; SolidLab Flanders)
Owner Sir Tim Berners-Lee (creator) / W3C Solid Community Group (specification); Open Data Institute (ODI) assumed stewardship October 2024 (Jesse Wright and Louise Burke); Inrupt (primary commercial entity, co-founded by Berners-Lee); W3C Linked Web Storage Working Group (LWS WG, launched 2024 for formal W3C Recommendations)
Country International (originally MIT/USA; ODI stewardship UK; Inrupt USA; LWS WG and Solid CG are W3C international)
Start Year 2016
Stack Implementation-dependent (Community Solid Server: TypeScript/Node.js; Node Solid Server: Node.js; other implementations in various languages; client libraries in JavaScript/TypeScript)
Funding Inrupt: VC ($30M Series A December 2021); ODI: various grants and memberships; EU funding (SolidLab, Kansen voor West program for Dutch Data Vault)
Last Investigated Jan 15, 2026

Use Case Domains

Identity & Trust Platform Evolution & Sovereignty

Affordances

Sovereign identity Data portability Self-hostable

Federated Protocol Attributes

Origins Semantic Web / Data sovereignty (Linked Data Platform evolution; Tim Berners-Lee's vision for re-decentralizing the web; built on decades of W3C Linked Data work)
Database Implementation-dependent (typically file-based RDF storage or triple stores; Pods store resources as HTTP-accessible files with RDF metadata)
Query Language SPARQL (for RDF data queries); also supports SPARQL UPDATE via HTTP PATCH; standard HTTP GET/PUT/POST/DELETE for resource operations
Data Formats RDF (Turtle, JSON-LD, RDFa, N-Triples) + any file type (Pods store both structured Linked Data and arbitrary files like images, documents)
Collaborative Live Editing Supported (via WebSockets and Solid Notifications Protocol for real-time updates; applications can subscribe to resource changes)
Rich Text Editing Application-level (not a protocol feature; applications built on Solid handle their own rendering)
Mobile Support Yes (any mobile app can access Solid Pods; reference apps exist)
Web Support Yes (primary target is web applications; browser-based Pod management and apps)
Native Apps Yes (any app can integrate Solid via standard HTTP and RDF; Solid apps are regular web apps that use Solid Pods for storage)
Terms Self-hosting (run own Pod server) + Pod providers (free/paid hosting; identity provider and Pod provider are separable services)
Funds $30M (Inrupt Series A, December 2021); EU funding for SolidLab Flanders and Dutch Data Vault Foundation
Based On Linked Data Platform (LDP, W3C Recommendation); HTTP; RDF (W3C); WebID (decentralized identity); Solid-OIDC (authentication based on OpenID Connect); WAC (Web Access Control)
Content Addressing No (location-based via HTTP URIs; resources identified by URL on Pod servers; not content-addressed)
E2EE Application-level (not mandated by protocol; Solid Protocol spec encourages privacy-preserving design per W3C Privacy Principles; encryption can be implemented by applications)
Signature WebID-based authentication (Solid-OIDC: WebID + OpenID Connect for decentralized cross-domain authentication; WebID-TLS as legacy method; TLS certificates for transport security)
Permissions Web Access Control (WAC) — ACL-based fine-grained permissions (read/write/append/control per resource); Access Control Policy (ACP) as alternative; per-resource and per-container access control
Semantic Web Compatibility RDF / Linked Data (core design principle; data stored as RDF using vocabularies and ontologies; SPARQL queries; enables machine-readable interoperable data across applications)
Federation Model Pod-based federation: Pods as personal data servers storing user data; applications access data from any Pod via standard HTTP/RDF protocols; apps and data are decoupled — any app can access any Pod with appropriate authorization; identity provider and Pod provider are separable
Instance / Server Requirements Low to moderate (Pod server can run on modest hardware; community implementations designed for easy self-hosting)
Account Portability Full portability (can move Pod between providers or self-host; data is in standard RDF/HTTP formats; WebID identity is separate from Pod location; no vendor lock-in by design)
Discovery / Relay Architecture WebFinger + WebID (decentralized discovery; WebID URIs point to WebID Profile documents containing user info, public keys, Pod locations, and preferences)
Server Authority Model User-controlled (Pod owner has full authority over their data; sets access control policies via WAC/ACP; applications request access; users grant/revoke permissions)
Protocol Maturity / Standardization W3C Community Group Reports (Solid CG specifications since 2018); W3C Linked Web Storage Working Group (LWS WG launched 2024) producing formal W3C Recommendations; not yet full W3C Recommendation status for core protocol
Data Sovereignty User-controlled (data in personal Pods; user chooses Pod provider or self-hosts; data independent of applications; German Bundeswehr and healthcare also evaluating Solid for sovereign data)