Catalogues / lists / repositories of open standards

Catalogues
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Online databases & lists of open standards

This is a curated overview of major directories, catalogues, registries and standards-developing organisations (SDOs) that publish or index open standards (specifications, protocols, file formats, ontologies, terminology systems, etc.). This is distinct from open software projects and open datasets — this list focuses on the technical specifications that enable interoperability. This is a wiki post, so you can add to this post; please feel free to enrich/improve where you can!!

All links were verified in May 2026.

1. Meta-directories & registries of standards

Resources whose primary content is other standards or standards bodies. The right starting point when you don’t yet know which body governs the specification you need.

  • FAIRsharing.org — ~3,500+ records across standards, databases, repositories and data policies (manually curated, interlinked). Covers ontologies, file formats, minimum reporting guidelines, identifier schemes and terminology artifacts, primarily in life sciences but expanding across all disciplines. The closest thing to a “Wikipedia of data standards.” (No single official live count is published on the JavaScript-rendered site; figure derived from FAIRsharing’s curator blog, Feb 2025.)
  • BARTOC — Basel Register of Thesauri, Ontologies & Classifications. The most important cross-domain meta-registry of knowledge organisation systems: ~10,000+ terminologies indexed, plus ~144 terminology registries. Spans classifications, thesauri, ontologies and authority files.
  • Bioregistry — Open metaregistry of biomedical prefixes, ontologies and databases; integrates ~23 external registries. Successor in spirit to identifiers.org.
  • RDA Metadata Standards Catalog (MSC) — Open catalogue of research-data metadata standards, profiles and tools, hosted at the University of Bath. (Supersedes the older read-only rd-alliance.github.io/metadata-directory.)
  • DCC Metadata Standards Catalogue — Digital Curation Centre’s curated list of disciplinary metadata standards, focused on research data archiving. Compact but authoritative.
  • OpenStand — Not a catalogue but the canonical statement of the principles of open standards, jointly affirmed by IEEE, IETF, IAB, ISOC and W3C. Useful as a definitional reference.
  • Public.Resource.Org / Law.Resource.Org — Carl Malamud’s nonprofit publishing free, public-domain copies of laws, regulations and standards incorporated by reference (ASTM, NFPA, ASHRAE, etc.). Won a landmark D.C. Circuit fair-use case in 2023. See also law.resource.org.
  • Perinorm / Accuris Standards Store — Commercial aggregators. Perinorm is a bibliographic database of ~2.7 million national/international standards records (DIN/BSI/AFNOR partnership). Accuris (formerly IHS Markit + Techstreet) is the principal commercial standards aggregator after the NSSN search engine was retired.
  • ANSI IBR Portal — Free read-only access to standards incorporated by reference in the US Code of Federal Regulations.
  • NYSED Standards & Specifications guide — Curated bibliography linking to >460 organisations worldwide publishing standards and specifications. Library-grade meta-list.
  • NSSN – National Standards System Network (legacy — search engine discontinued) — Formerly indexed 225,000+ standards across U.S., international and national bodies. nssn.org now redirects to ANSI’s “StandardsLearn” educational portal; the cross-SDO search functionality has been retired. Use the ANSI Webstore, ANSI IBR Portal, or Accuris instead.

2. International / global standards bodies

The largest formal SDOs whose catalogues function as primary references. Some standards here are open (free to read/implement); others are RAND/FRAND-licensed; the line is debated. All are publicly searchable catalogues.

  • ISO – International Organization for Standardization — 25,000+ International Standards and related documents (ISO’s own current wording). Covers virtually every industry; sold per-document (not free), but ISO also publishes open machine-readable metadata on its standards.
  • IEC – International Electrotechnical Commission — ~10,500–11,000 international standards (incl. TS, TR, PAS) for electrical, electronic and related technologies. Often paired with ISO (ISO/IEC joint publications).
  • IEEE Standards Association (IEEE-SA) — Major global SDO: ~1,300 active standards, 500+ in development. The 802 networking family, the P7000 AI-ethics series, power, biometrics. A curated subset is free via the IEEE GET Program (e.g. the 802 family six months after publication; the P7000 AI-ethics series).
  • ITU-T Recommendations — ~3,000+ Recommendations for telecommunications and ICT. Free to download since 2007 (except ~30 joint ITU-T | ISO/IEC documents). The “T” series; see also ITU-R (radiocommunication / spectrum) and ITU-D (development).
  • CEN-CENELEC catalogue — European Committees for Standardization. Joint catalogue of European Standards (ENs), Technical Specifications and other deliverables, including those harmonised under EU regulations.

3. Internet & Web standards

The standards bodies that built and maintain the open Internet and Web stack. Distinguished by genuinely free, open access to specifications.

  • IETF / RFC Editor — ~10,000 RFCs (over 9,960 as of May 2026), of which a subset are “Internet Standards” (STDs) and “Best Current Practices” (BCPs). Covers TCP/IP, HTTP, TLS, DNS, SMTP, IMAP, OAuth, etc. Fully free to download; the foundational catalogue of internet protocols. Work-in-progress drafts at the IETF Datatracker.
  • W3C – World Wide Web Consortium — Hundreds of Recommendations (W3C’s term for ratified standards) plus many Working Drafts and Notes; canonical listing at w3.org/TR/. Covers HTML, CSS, SVG, WCAG, RDF, DOM, WebRTC, decentralised identifiers, etc. (Reorganised as a US 501(c)(3) non-profit in January 2023.)
  • WHATWG — ~10 Living Standards including the HTML and DOM specifications. Continuously updated (no versioned “snapshots”).
  • Ecma International — >420 ECMA Standards + >110 Technical Reports, including ECMAScript (JavaScript), JSON, C# and CLI. About two-thirds also published as ISO/IEC. Free to download.
  • Unicode Consortium — The Unicode Standard plus ~20 Unicode Technical Standards (UTS) and Reports (UTR). The base of text encoding worldwide.
  • IANA Protocol Registries — Master registry of IETF protocol parameters: port numbers, URI schemes, MIME media types, HTTP fields, BCP/STD numbers, MIB OIDs, etc.; ~3,000+ individual registries.
  • ICANN — Coordinates the DNS root, IP allocation and gTLD policy. A governance body that delegates to IETF/IANA rather than a strict SDO, but indispensable to the open Internet.
  • schema.org — Cross-search-engine vocabulary (Microdata / RDFa / JSON-LD); v30.0 (stable) published 19 March 2026. ~800+ types and ~1,500+ properties.
  • JSON Schema — De facto standard for JSON validation; currently being progressed through the IETF; latest draft 2020-12.
  • GraphQL — Query language and runtime (spec); governed by the GraphQL Foundation under the Linux Foundation.
  • AsyncAPI — Open spec for event-driven / asynchronous APIs (Linux Foundation); v3.0 (December 2023).
  • OpenTelemetry and CloudEvents — CNCF-graduated observability and event-description specs (OTLP, Semantic Conventions; CloudEvents v1.0.2).
  • JSON-LD — W3C Recommendation for JSON-based Linked Data; current 1.1.

3a. Decentralised / identity / trust protocols

The building blocks of a privacy-first, federated, European-sovereignty stack — currently the most fast-moving open-standards layer.

  • ActivityPub (W3C) — Decentralised social-networking protocol (W3C Recommendation, 2018); the foundation of the Fediverse (Mastodon, PeerTube, Lemmy, Pixelfed, and Threads federation).
  • Matrix — Open standard for secure, decentralised real-time communication (Matrix.org Foundation). Deployed by the French state (Tchap), the German Bundeswehr (BwMessenger), German healthcare (TI-Messenger) and many EU public-sector users.
  • XMPP Standards Foundation — Federated messaging via XEPs; still relevant for IoT and federated chat.
  • OpenID Foundation — Identity standards: OpenID Connect (OIDC), FAPI, Verifiable Credentials, eKYC/IDA; 30+ active specifications.
  • FIDO Alliance — Passwordless / phishing-resistant authentication: FIDO2 (= WebAuthn + CTAP), passkeys, UAF, U2F. WebAuthn is the W3C side; CTAP the FIDO side.
  • IETF OAuth Working Group — OAuth 2.0 (RFC 6749), OAuth 2.1 in progress, DPoP, PAR, RAR.
  • IndieWeb — Community of personal-website / federated standards: Microformats, Webmention, IndieAuth, Micropub (all W3C Recommendations).

4. Industry consortium standards (open specifications)

Membership-driven consortia that publish royalty-free or RAND-licensed open specifications, often filling gaps left by formal SDOs.

  • OASIS Open — ~80+ OASIS Standards and many more Committee Specifications. Covers OpenDocument (ODF), SAML, OData, MQTT, AMQP, STIX/TAXII, DocBook, CAP/EDXL emergency standards. Several OASIS standards (e.g. ODF, MQTT, AMQP) also become ISO standards.
  • OMG – Object Management Group — ~200+ specifications across Business Modeling, Healthcare, Finance, Government, Lifesciences, etc. Home of UML, BPMN, DDS, CORBA.
  • OGC – Open Geospatial Consortium — 80+ adopted standards (150+ including profiles and encodings) for geospatial information: WMS, WFS, GeoPackage, CityGML, SensorThings, openEO.
  • OpenAPI Initiative — The OpenAPI Specification (formerly Swagger). Hosted under the Linux Foundation.
  • The Open Group Library — Standards including TOGAF, ArchiMate, O-PAS, Open FAIR. Strong in enterprise architecture. (Publications library; standards landing page at opengroup.org/standards.)
  • Khronos Group Registry — Open standards for graphics, AR/VR, parallel computing: OpenGL, Vulkan, OpenCL, glTF, OpenXR, WebGL. (The registry is the actual spec repository; the main site covers governance.)
  • Open Container Initiative (OCI) — Open specifications behind container images: the Image, Runtime and Distribution specs underpinning Docker, Podman and Kubernetes. Linux Foundation project; specs at opencontainers.org.
  • 3GPP — Mobile telecom (2G–6G); organised by quarterly Releases (Rel-18/19 ongoing, Rel-20 “5G-Advanced” in 2026). Thousands of TS/TR documents; the standards behind GSM, LTE and 5G NR.
  • GSMA — Mobile-operator industry body: RCS Universal Profile, eSIM (SGP.21/.22/.32), Open Gateway / CAMARA APIs.
  • IEEE 802 LAN/MAN Standards Committee — 802.3 Ethernet, 802.11 Wi-Fi, 802.1 bridging, 802.15 (Bluetooth/Thread/Zigbee PHY). Free via the IEEE GET Program six months after publication.
  • OPC Foundation (OPC UA) — Industrial automation interoperability; OPC UA standardised as IEC 62541; 30+ companion specs. Central to European industrial sovereignty (RAMI 4.0, Plattform Industrie 4.0).
  • Connectivity Standards Alliance (Matter / Zigbee) — Matter 1.5.x smart-home spec; Zigbee PRO; Aliro access control. 550+ member companies.
  • Thread Group, LoRa Alliance, Bluetooth SIG, Modbus Organization — IoT / networking / industrial protocols (Thread mesh over 802.15.4; LoRaWAN LPWAN; Bluetooth Core / LE Audio / Mesh; Modbus RTU/TCP).
  • Broadband Forum — Broadband network specs: TR-069 / TR-369 USP, TR-181 data model. ~400+ Technical Reports.
  • FIX Trading Community and ACORD — FIX Protocol for electronic trading; ACORD insurance data standards.

5. European / regional standards bodies

Bodies producing standards scoped to a region, often with strong relevance to interoperability obligations under EU law. Especially relevant to digital-sovereignty and public-procurement work.

  • ETSI – European Telecommunications Standards Institute — Publishes ~2,500+ standards per year (56,000+ total catalogue) across ICT (GSM, 3G/4G/5G, DECT, NFV, eIDAS-related signature standards). PDFs free to download (Word version restricted). Host of the 3GPP series.
  • CEN and CENELEC — European Standards (ENs) developed under Regulation 1025/2012, often harmonised under EU directives (CE marking).
  • Interoperable Europe Portal (renamed from Joinup, November 2024) — European Commission portal cataloguing interoperability solutions, semantic assets and references to open standards/specifications used by EU public administrations. Mandatory reference point under the Interoperable Europe Act (Reg. EU 2024/903).
  • NIFO – National Interoperability Framework Observatory / EIF — The European Interoperability Framework and its observatory; recommended standards and specifications for cross-border e-government services. (The “CEF Digital” brand has been retired.)
  • EUDI Wallet Architecture Reference Framework (ARF) — Open GitHub repository for the EU Digital Identity Wallet under eIDAS 2.0; ARF v2.0 (May 2025). Reference implementations (iOS, Android, web verifier) under the eu-digital-identity-wallet org. High-priority for privacy-first mobile-OS work.
  • ENISA standards work — EU Agency for Cybersecurity; coordinates the EUCC, EUCS and EU5G certification schemes under the EU Cybersecurity Act.
  • EN 301 549 (search “EN 301 549”) — Harmonised European Standard for ICT accessibility; mandatory under the EU Web Accessibility Directive and the European Accessibility Act; references WCAG 2.1 AA (v4.x planned to align with WCAG 2.2). Jointly produced by CEN / CENELEC / ETSI.
  • INSPIRE Knowledge Base — EU Directive 2007/2/EC spatial-data infrastructure; 34 spatial-data themes (Annexes I–III); binding for EU public-sector geodata.
  • CAMSS — Common Assessment Method for Standards and Specifications; the EU method for assessing whether a standard meets openness/interoperability criteria, used in procurement.
  • SEMIC and DCAT-AP — Semantic Interoperability Community; maintains the Core Vocabularies (Core Person, Business, Location, Public Service) and the Data Catalogue Vocabulary Application Profile for European data portals.
  • DIN (DE), AFNOR (FR), BSI (UK), NEN (NL) — National standards bodies, each publishing thousands of national standards and acting as the national entry point to ISO/CEN.

6. National & government standards portals

Government-published catalogues of standards mandated, recommended or adopted for public procurement — including “comply-or-explain” frameworks.

  • Forum Standaardisatie / pas-toe-of-leg-uit lijst (Netherlands) — Dutch government’s official “comply-or-explain” list of ~50 mandatory open standards (binding for public IT procurement above €50,000) plus a recommended list. The most mature such framework in Europe; strong reference for digital-sovereignty work.
  • XÖV / KoSIT and IT-Planungsrat (Germany) — XML data-exchange framework for German public administration (XMeld, XRechnung, XBau, XZuFi, XDatenfelder…); 30+ XÖV standards, published via the XRepository. The key German government open-standards body.
  • ZenDiS / openDesk / openCode (Germany) — German Centre for Digital Sovereignty. Develops openDesk (open-source M365 alternative bundling Nextcloud, Open-Xchange, Element/Matrix, Collabora, etc.) and openCode (GitLab-based public-sector OSS forge). Critical sovereignty reference.
  • Sovereign Tech Agency (Germany) — Government-funded body (SPRIND subsidiary) investing in open-source critical infrastructure; runs the Sovereign Tech Fund, Resilience, Fellowship and (2025–) Sovereign Tech Standards programmes. ~€23.5 M invested across 60 critical technologies (Log4j, Samba, GNOME, etc.) as of November 2024.
  • Référentiel Général d’Interopérabilité (RGI) (France) — Mandatory French government interoperability reference (V2.0, 2016). Companion: RGAA (accessibility).
  • X-Road / X-tee (Estonia / NIIS) — Open-source secure data-exchange layer (MIT licence), developed by the Nordic Institute for Interoperability Solutions (Estonia + Finland + Iceland); used by 20+ countries. Estonian deployment: RIA X-tee.
  • NIST CSRC (USA) — Computer Security Resource Center; FIPS standards, the SP 800 series (~200+ publications), the NIST Cybersecurity Framework 2.0 (2024).
  • NIST standards.gov hub (USA) — U.S. government’s hub for federal, industry and international standards engagement.
  • NISO – National Information Standards Organization (USA) — ANSI-accredited SDO for library / publishing / information services (Z39 series, JATS, KBART, OpenURL); 70+ active standards and recommended practices.
  • ANSI Webstore (USA) — American National Standards Institute. Index to U.S. national standards (~10,000+ ANS designations) plus distribution of ISO/IEC.
  • NASA Technical Standards System (USA) — Thousands of standards accessible (NASA-authored plus subscribed SDB content); free read access for NASA-preferred standards.
  • GOV.UK Open Standards (UK) — UK government’s adopted open standards for software interoperability, data and document formats.
  • Other national comply-or-explain frameworks — Denmark (digst.dk), Italy (AgID Linee Guida), Spain (Esquema Nacional de Interoperabilidad). Less centrally maintained than the Dutch list, but analogous instruments.

7. Domain-specific standards registries

Catalogues focused on a single domain — useful when you know the field. (Note: BioPortal, OBO Foundry, OLS4 and Ontobee index largely the same biomedical ontologies through different lenses; don’t count ontologies across them independently.)

Semantic web / ontology registries

  • BioPortal — 1,549 ontologies (1,182 public), 15.3 million terms, 100 million+ cross-ontology mappings (NCBO, 2025). The reference registry for biomedical semantic standards.
  • EBI Ontology Lookup Service (OLS4) — ~278 ontologies, ~10.2 million classes, ~50,000 properties (EMBL-EBI). OLS4 replaced OLS3 in production in 2024.
  • Ontobee — Linked-data server for ontologies; the default Linked-Data browser used by OBO Foundry; ~180+ ontologies.
  • OBO Foundry — ~175 active, orthogonally-designed biomedical ontologies sharing common principles (Gene Ontology, Disease Ontology, ChEBI, etc.), plus candidates and obsolete entries.
  • AgroPortal — Agronomy-focused ontology repository (~150+ ontologies). Part of the OntoPortal family (alongside EcoPortal, IndustryPortal, MedPortal).
  • Linked Open Vocabularies (LOV) — ~900 RDF vocabularies for the linked-data web, with quality metadata and cross-references.
  • Research Vocabularies Australia — Hundreds of vocabularies, hosted by the Australian Research Data Commons.
  • Dublin Core Metadata Initiative — DCMI Metadata Terms and related specifications, foundational for library, archive and digital-object metadata.

Healthcare / life science

  • HL7 — Healthcare interoperability standards: HL7 v2, v3, CDA, and FHIR (the current dominant standard for health data exchange). Community FHIR implementation guides and packages at Simplifier.net (~5,000+ projects).
  • SNOMED International — SNOMED CT clinical terminology (~370,000+ active concepts). Open within member countries.
  • LOINC — Universal terminology for lab tests, clinical observations and document types; ~100,000+ active terms (Regenstrief Institute).
  • DICOM — Medical imaging standard (PS3, multi-part), maintained by NEMA/MITA.
  • openEHR International — Open clinical EHR architecture (Reference Model + Archetypes + Templates); Clinical Knowledge Manager hosts 700+ published archetypes. Relevant for European e-health sovereignty.
  • IHE – Integrating the Healthcare Enterprise — Profiles combining HL7/DICOM/etc. to solve interoperability use cases; ~150+ profiles across ~14 clinical domains.
  • WHO ICD-11 — International Classification of Diseases, 11th revision (effective 2022); ~17,000 diagnostic categories, ~120,000 codable terms.

Geospatial

  • ISO/TC 211 — Geographic Information / Geomatics; the ISO 19100 series (~80+ standards). Works closely with OGC. (See also INSPIRE in the European section.)

Financial / business

  • ISO 20022 — Financial messaging standard; ~284 message sets and 750+ individual message definitions.
  • GLEIF / LEI (ISO 17442) — Global Legal Entity Identifier Foundation; 3.02 million active LEIs as of end-Q1 2026 (+13.5% in 2025).
  • GS1 Standards — Global standards for product identification, barcodes, EPCIS supply-chain events.
  • IFRS / IFRS Sustainability Standards — Accounting and sustainability reporting standards. Some content open; full standards via subscription.
  • XBRL International — XBRL specifications for business and financial reporting in machine-readable form.

Identifiers / persistent IDs

Library / archives

  • Library of Congress standards hub — Central hub for METS, MODS, PREMIS, MARC, MARCXML, EAD, BIBFRAME, MIX and MADS. The single most important resource for the library/archives community.

8. Open document & file format standards

A useful slice given how often “open standard” debates centre on document formats and codecs.

9. Specialised open-standards advocacy & comparison resources

Smaller resources useful for political/strategic context on what counts as “open.”

10. Open hardware & silicon standards

Open specifications for hardware and chip design — increasingly central to European semiconductor sovereignty under the EU Chips Act.

  • RISC-V International — Open ISA stewards (Linux Foundation member); ~55+ ratified specifications, ~75 technical working groups. Ratified-extensions library at docs.riscv.org.
  • Open Compute Project (OCP) — Open hardware designs for data centres (servers, racks, networking, AI accelerators).
  • CHIPS Alliance — Linux Foundation project for open hardware IP (RISC-V cores, networking, SSDs).
1 Like
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Nice catalogue. Thanks.

3

Thanks for posting! :star_struck: