W System / Data sources and licences
Data sources and licences
W System answers VAT, EORI, sanctions, company-register and KYB checks from official public-sector sources. This page lists each upstream source, who owns it, the licence or terms we reuse it under, and the attribution that goes with it. Every API result also names its source in the source field.
W System is an independent service. None of the bodies below endorses, approves or is affiliated with W System, and their names are used only to identify where the data comes from. Their logos are not used.
Last reviewed: 22 October 2026.
VAT and customs (EORI)
| Source | Owner | Licence / terms | Attribution |
|---|---|---|---|
| VIES VAT number validation (used for EU-27 and XI Northern Ireland VAT numbers) | European Commission, DG TAXUD; the answers come from the member states' tax administrations | Public validation service. Commission content is reused under Commission Decision 2011/833/EU (CC BY 4.0 by default). The VAT data itself belongs to the member states. | "VAT validation: VIES, European Commission (DG TAXUD), with data from EU member-state tax administrations. Commission content reused under Decision 2011/833/EU." |
| EOS EORI number validation | European Commission, DG TAXUD | Public validation service; Commission Decision 2011/833/EU. Names and addresses appear only where the trader has agreed to publication. | "EORI validation: EOS, European Commission (DG TAXUD). Reused under Decision 2011/833/EU." |
| Wykaz podatników VAT (VAT taxpayer white list), used only as a fallback when VIES cannot answer for Poland | Ministry of Finance / National Revenue Administration (KAS), Poland | Public, free API (wykazpodatnikowvat.mf.gov.pl) under the Ministry's published conditions. | "Source: Wykaz podatników VAT, Ministry of Finance of the Republic of Poland." |
| HMRC "Check a UK VAT number" API (UK GB VAT numbers) | HM Revenue & Customs, United Kingdom | Not in use yet. UK (GB) VAT checks are coming soon: until our HMRC production access is granted, GB numbers return member_state_unavailable and are not checked or charged. Once live, use will follow the HMRC Developer Hub terms of use. | Once live: "UK VAT data: HM Revenue & Customs, Check a UK VAT number API." |
Sanctions lists
| Source | Owner | Licence / terms | Attribution |
|---|---|---|---|
| EU Consolidated Financial Sanctions List | European Commission (Financial Sanctions Files) | Commission Decision 2011/833/EU (reuse of Commission documents). | "EU Consolidated Financial Sanctions List, © European Union. Reused under Decision 2011/833/EU." |
| OFAC Specially Designated Nationals (SDN) and consolidated lists | U.S. Department of the Treasury, Office of Foreign Assets Control | U.S. Government work, public domain (17 U.S.C. §105). | "Source: U.S. Department of the Treasury, Office of Foreign Assets Control (OFAC)." (not required, given as good practice) |
| UK Sanctions List | Foreign, Commonwealth & Development Office (FCDO), United Kingdom | Open Government Licence v3.0. | "Contains public sector information licensed under the Open Government Licence v3.0." Source: UK Sanctions List, FCDO. |
| United Nations Security Council Consolidated List | United Nations Security Council Secretariat | Published by the UN so that Member States and others can implement sanctions measures. No specific open-data licence is published for it. We use the list as published, without altering listings. | "Source: United Nations Security Council Consolidated List (scsanctions.un.org)." |
Company registers
| Source | Owner | Licence / terms | Attribution |
|---|---|---|---|
| LEI data (any country without a national register below, and GB) | Global Legal Entity Identifier Foundation (GLEIF) | CC0 1.0 (GLEIF LEI data terms of use). | "LEI data: GLEIF, CC0 1.0." (not required, given as good practice) |
| Recherche d'entreprises API (Sirene data), France | DINUM, with data from INSEE (Sirene register) | Licence Ouverte / Open Licence 2.0 (Etalab). | "Source: Recherche d'entreprises (DINUM), INSEE Sirene data, Licence Ouverte 2.0. Data retrieved live at the time of each request." |
| Enhetsregisteret (Central Coordinating Register for Legal Entities), Norway | Brønnøysund Register Centre (Brønnøysundregistrene) | Norwegian Licence for Open Government Data (NLOD) 2.0. | "Contains data under the Norwegian licence for Open Government data (NLOD) made available by the Brønnøysund Register Centre." |
| YTJ open data API, Finland | Finnish Patent and Registration Office (PRH) | CC BY 4.0. | "Source: Finnish Patent and Registration Office (PRH), YTJ open data, CC BY 4.0." |
| ARES (register of economic entities), Czech Republic | Ministry of Finance of the Czech Republic | Public, free REST API under the Ministry's published operating conditions (no specific open licence). | "Source: ARES, Ministry of Finance of the Czech Republic." |
| KRS open API (National Court Register), Poland | Ministry of Justice of the Republic of Poland | Open data under the KRS Act (art. 4b) and the Polish Open Data Act of 2021. | "Source: Krajowy Rejestr Sądowy (KRS), Ministry of Justice of the Republic of Poland. Data obtained at the time of each request." |
| e-Business Register autocomplete service, Estonia | Centre of Registers and Information Systems (RIK) | Public service; open data under CC BY 4.0. | "Source: Estonian e-Business Register, Centre of Registers and Information Systems (RIK), CC BY 4.0." |
Notes
- Results reflect what each source returned at the time of the request. A fallback answer (
fallback: true) is never a VIES confirmation and carries no consultation number. - Some register results can include sole traders, whose details are personal data. See the privacy policy.
- Questions about a source or attribution: [email protected].