BIPM - Bureau International de Poids et Mesures
- https://www.bipm.org/en/home
- https://www.bipm.org/kcdb/ (KCDB is the Key Comparison Data Base of the BIPM)
- https://www.bipm.org/en/time-metrology
- https://www.bipm.org/en/time-ftp/
Germany
- Clock - https://uhr.ptb.de/ (including Δt to local device)
- UTC(PTB)
- Metrological services - https://www.ptb.de/cms/en/metrological-services.html
Norway
- Justervesenet (Norwegian Metrology Service): https://www.justervesenet.no/en/ ; https://www.justervesenet.no/maleteknikk/tid-og-frekvens/noyaktig-tid/
Poland
- UTC(PL)
- UTC(AOS)
Serbia
- Clock - https://www.dmdm.rs/en/
- UTC+1 (Belgrade, Serbia)
Switzerland
- UTC(CH)