Uniform Resources

Semantic & Data Protocol

Specification for encoding CBOR (and Gordian Envelopes) as plain-text URIs that are also QR-code-friendly. Provides a typed URI scheme (ur:type/...), Bytewords minimal encoding for ASCII safety, multipart sequencing (MUR) for data exceeding single-QR capacity, and Luby Transform fountain codes that allow an animated QR sequence to begin at any frame and tolerate missing frames. Widely adopted across the Bitcoin self-custody ecosystem (Sparrow Wallet, Foundation Devices Passport, Keystone, etc.) for airgapped PSBT signing and seed/key transmission. Supports both bare URs (single CBOR data items) and Envelope-wrapped URs (recommended for richer use cases). Sub-specs include MUR (Multipart UR), Bytewords encoding, and a registry of UR types and CBOR tags

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Details

License BSD-2-Clause Plus Patent License — bc-ur (C++), URKit (Swift), bc-ur-rust, @ngraveio/bc-ur (JavaScript), and multiple third-party implementations
Dev Status 🟢 Active
Dev Status Detail Released — production; widely adopted in Bitcoin wallet ecosystem; reference libraries in C++, Swift, Rust, TypeScript, JavaScript, Python, Java
Owner Blockchain Commons LLC (not-for-profit benefit corporation founded by Christopher Allen, April 25, 2019; Berkeley, California). Specification authors: Wolf McNally, Christopher Allen
Owner - List
  • Blockchain Commons
Governing Body Blockchain Commons LLC (not-for-profit benefit corporation; CBOR tags registered in the IANA registry)
Governing Body - List
  • Blockchain Commons
Country USA (Berkeley, California)
Start Year 2020
Stack Reference libraries: C++ (bc-ur), Swift (URKit), Rust, TypeScript, plus third-party Java (Sparrow Wallet) and Python (Foundation Devices) implementations
Funding Blockchain Commons donations and patron sponsorships
Funding - List
  • Blockchain Commons
Last Investigated Jul 1, 2026

Topology view

This tool in the centre and the things it is directly related to. Each line names the kind of relationship.

Topology view: Uniform ResourcesThis tool in the centre and the things it is directly related to. Each line names the kind of relationship.UniformResourcesBitcoin (Based on)BitcoindCBOR (Based on, Composes with, Speaks protocol)dCBORGordian Clubs (Composes with)GordianClubsGordian Envelope (Composes with)GordianEnvelopeHubert (Composes with)HubertSSKR (Composes with)SSKRXID (Composes with)XIDBlockchain Commons (Developed by, Funded by, Stewarded by)BlockchainCommonsGordian Suite (Member of suite)GordianSuite
  • Bitcoin (Tool): Based on
  • dCBOR (Tool): Based on, Composes with, Speaks protocol
  • Gordian Clubs (Tool): Composes with
  • Gordian Envelope (Tool): Composes with
  • Hubert (Tool): Composes with
  • SSKR (Tool): Composes with
  • XID (Tool): Composes with
  • Blockchain Commons (Organization): Developed by, Funded by, Stewarded by
  • Gordian Suite (Suite): Member of suite

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Use Case Domains

Co-Creation & Knowledge

Affordances

Interoperable formats Data portability

Semantic & Data Protocol Attributes

Owner - List
  • Blockchain Commons
Origins Blockchain Commons; designed initially for airgapped PSBT (Partially Signed Bitcoin Transaction) transmission
Database N/A — encoding specification, not a storage system
Query Language N/A — encoding specification
Data Formats CBOR (deterministic, via dCBOR for Envelope-wrapped URs); Bytewords minimal encoding (base-32 ASCII subset compatible with QR alphanumeric mode and URI syntax); type-prefixed UR scheme (ur:seed/, ur:psbt/, etc.)
Collaborative Live Editing N/A — encoding specification
Rich Text Editing N/A — encoding specification
Mobile Support Yes — primary use case is mobile QR-based airgap transmission
Web Support Yes (JavaScript and TypeScript libraries)
Native Apps Yes — adopted by hardware wallets (Foundation Devices Passport, Keystone), desktop wallets (Sparrow), reference apps (Gordian Seed Tool, URDemo)
Terms Open standard, BSD-2-Clause Plus Patent License
Funding - List
  • Blockchain Commons
Funds Unknown — funded under Blockchain Commons general operating budget; specific UR allocation not separately published
Based On CBOR (RFC 8949); RFC 3986 (URI syntax); QR Code alphanumeric mode; CRC-32; Luby Transform fountain codes (for MUR)
Governing Body - List
  • Blockchain Commons
Semantic Web Compatibility UR types provide self-describing data tagging; not RDF-semantic but enable interoperable interpretation of binary cryptographic data across implementations
Protocol Maturity / Standardization Production-ready; widely adopted across the Bitcoin self-custody ecosystem; CBOR tags registered in IANA registry; revised April 2025 (BCR-2020-006 v2 types and tags)
Vocabulary / Ontology Type Type registry (BCR-2020-006) of UR types and CBOR tags maintained by Blockchain Commons (registered in IANA CBOR Tags Registry); covers seed, hdkey, psbt, output-descriptor, sskr, envelope, xid, and others
Usage Pattern Airgapped data transmission (especially PSBT signing); QR-encoded transport of seeds, keys, descriptors, Envelopes; hardware-wallet-to-coordinator communication; multi-party ceremony coordination

Relationships

How this tool connects to other tools and organizations, from relationships reviewed by the OpenHaven data steward. They describe how projects connect, not how good they are.

Based on
Developed by
  • Blockchain Commons
Funded by
  • Blockchain Commons
Member of suite
  • Gordian Suite
Speaks protocol
Stewarded by
  • Blockchain Commons
Composes with