more information - https://www.bipm.org/en/about-us.
I will list only publicly available servers, not the ones that require prior requests for access (e.g. Australia, Luxembourg, Costa Rica, Panama).
Time Dissemination services are documented here as of the 2025 edition (information received at the BIPM February–March 2026)
Rolling "latest edition" URL: https://webtai.bipm.org/ftp/pub/tai/annual-reports/bipm-annual-report/TIMESERVICES/timeservices.pdf
Entries marked (unconfirmed) are based on the 2024 annual report and were not confirmed by the laboratory for the 2025 edition.
| Country | Institute | Servers | Notes |
|---|---|---|---|
| Argentina | AGGO - Argentinean-German Geodetic Observatory | ntp.aggo-conicet.gob.ar | stratum 1, open access |
| Argentina | IGN - National Geographic Institute | ntp.ign.gob.ar | stratum 2, open access (unconfirmed) |
| Argentina | INTI - National Institute of Industrial Technology | ntp.inti.gob.ar | open access |
| Austria | BEV - Federal Office of Metrology and Surveying | bevtime1.metrologie.at bevtime2.metrologie.at time.metrologie.at |
NTP + NTS |
| Belarus | BelGIM | time.belgim.by | stratum 1 |
| Belgium | ORB - Royal Observatory of Belgium | ntp-public-1.oma.be ntp-public-2.oma.be |
stratum 2 free; stratum 1 free after validation via ntp-as@oma.be; https://betime.be |
| Belgium | SMD - FPS Economy | ntp1.economie.fgov.be ntp2.economie.fgov.be ntp3.economie.fgov.be |
free access |
| Bosnia and Herzegovina | IMBH - Institute of Metrology | ntp1.imbih.gov.ba ntp2.imbih.gov.ba |
stratum 1 |
| Brazil | ONRJ - National Observatory | 200.20.186.75 200.20.186.94 |
|
| Brazil | LRTE - Time and Space Reference Laboratory, University of São Paulo | lrtest1.ntp.ifsc.usp.br (S1) lrtest2.ntp.ifsc.usp.br (S2) |
free access |
| Canada | NRC - National Research Council | time.nrc.ca time.chu.nrc.ca |
|
| China | NIM - National Institute of Metrology | ntp1.nim.ac.cn ntp2.nim.ac.cn |
free access |
| China | NTSC - National Time Service Center, Chinese Academy of Sciences | ntp.ntsc.ac.cn | free access; see http://www.ntsc.ac.cn/ |
| Colombia | INM - National Metrology Institute | ntp1.inm.gov.co ntp2.inm.gov.co |
open access |
| Croatia | IFZG - Institute of Physics | time.ifs.hr | stratum 1 |
| Czechia | Institute of Photonics and Electronics, Czech Academy of Sciences | ntp.ufe.cz | |
| Denmark | DFM - Danish National Metrology Institute | time.dfm.dk | NTP + NTS, free access |
| Finland | VTT MIKES - Centre for Metrology | time.mikes.fi time1.mikes.fi time2.mikes.fi |
stratum 2 free; stratum 1 is a paid service |
| France | LNE-OP - Observatoire de Paris | ntp.obspm.fr | stratum 2, free; the stratum 1 server ntp-p1.obspm.fr is restricted |
| Germany | PTB - Physikalisch-Technische Bundesanstalt | ptbtime1.ptb.de ptbtime2.ptb.de ptbtime3.ptb.de ptbtime4.ptb.de |
NTP + NTS |
| Hong Kong | HKO - Hong Kong Observatory | stdtime.gov.hk stdtime.hko.gov.hk time.hko.hk (IPv6) |
|
| India | CSIR - National Physical Laboratory | time.nplindia.org time.nplindia.in |
stratum 1, round robin |
| Indonesia | SNSU-BSN - National Standardization Agency | ntp.bsn.go.id | stratum 1, free access |
| Italy | INRIM - Istituto Nazionale di Ricerca Metrologica | ntp1.inrim.it ntp2.inrim.it |
|
| Jamaica | BSJ - Bureau of Standards Jamaica | 66.249.155.4 | stratum 1 |
| Japan | NAO - National Astronomical Observatory | s2csntp.miz.nao.ac.jp | stratum 2, round robin (unconfirmed) |
| Japan | NICT - National Institute of Information and Communications Technology | ntp.nict.jp | stratum 1, round robin |
| Kazakhstan | Kazakhstan Institute of Standardization and Metrology | ntp1.ksm.kz ntp2.ksm.kz ntp3.ksm.kz |
stratum 1 |
| Lithuania | LT - Center for Physical Sciences and Technology | laikas2.pfi.lt | free access |
| Mexico | CENAM - Centro Nacional de Metrología | (see link) | three stratum 1 servers; hostnames at https://www.cenam.mx/hora_oficial/sincronia.aspx |
| Mongolia | MASM - Agency for Standardization and Metrology | ntp.mn (within Mongolia) master.ntp.mn |
free access (unconfirmed) |
| Netherlands | VSL National Metrology Institute | ntp.vsl.nl ntp1.vsl.nl |
ntp2.vsl.nl exists but is access-by-registration only |
| New Zealand | MSL - Measurement Standards Laboratory | pool.msltime.measurement.govt.nz msltime1.measurement.govt.nz |
access for users within New Zealand |
| North Macedonia | BoM - Bureau of Metrology | time.bom.gov.mk | stratum 1 + stratum 2 (unconfirmed) |
| Norway | Justervesenet - Norwegian Metrology Service | ntp.justervesenet.no | stratum 1, open access |
| Poland | AOS - Astrogeodynamical Observatory, Borowiec | ntp.cbk.poznan.pl | open access |
| Poland | GUM - Central Office of Measures | tempus1.gum.gov.pl tempus2.gum.gov.pl tempus3.gum.gov.pl |
open access; authenticated NTP keys via https://e-czas.gum.gov.pl |
| Romania | NIMB - National Institute of Metrology | ntp.inm.ro | stratum 1, open access (unconfirmed) |
| Russia | VNIIFTRI - All-Russian Scientific Research Institute for Physical Technical and Radiotechnical Measurements | ntp1.vniiftri.ru ntp2.vniiftri.ru ntp3.vniiftri.ru ntp4.vniiftri.ru ntp1.niiftri.irkutsk.ru ntp2.niiftri.irkutsk.ru ntp.sstf.nsk.ru ntp.sniim.ru vniiftri.khv.ru vniiftri2.khv.ru ntp.kam.vniiftri.net ntp21.vniiftri.ru (S2) |
12× stratum 1, 1× stratum 2 |
| Saudi Arabia | SASO - Saudi Standards, Metrology and Quality Organization | time.saso.gov.sa | |
| Serbia | DMDM - Directorate of Measures and Precious Metals | vreme1.dmdm.rs vreme2.dmdm.rs |
stratum 2, free; also reachable as vreme1/vreme2.dmdm.gov.rs; the stratum 1 servers are restricted |
| Singapore | National Metrology Centre, A*STAR | nets.org.sg | NTP, Time and Daytime protocols |
| Slovenia | SIQ Ljubljana | ntp.siq.si time.siq.si |
free access; both names point to the same server |
| South Africa | NMISA - National Metrology Institute | time.nmisa.org | open access |
| South Korea | KRISS - Korea Research Institute of Standards and Science | ntp.kriss.re.kr | public server is stratum 3, cloud-hosted; stratum 1/2 are not for service |
| Spain | ROA - Spanish Navy Observatory | hora.roa.es minuto.roa.es nts1.roa.es (NTS) |
|
| Sri Lanka | MUSSD - Measurement Units, Standards and Services Department | sltime.org | see http://www.sltime.org (unconfirmed) |
| Sweden | RISE Research Institutes of Sweden | nts1.ri.se (NTP + NTS) nts2.ri.se (NTP + NTS) ntp1.sp.se ntp2.sp.se ntp3.sp.se ntp4.sp.se |
IPv4 + IPv6 |
| Switzerland | METAS - Federal Institute of Metrology | ntp.metas.ch ntp11.metas.ch ntp12.metas.ch ntp13.metas.ch |
stratum 1, open access; ntp.metas.ch is an alias that dynamically points to one of the three |
| Taiwan | TL - Telecommunication Laboratories, Chunghwa Telecom | time.stdtime.gov.tw clock.stdtime.gov.tw tick.stdtime.gov.tw tock.stdtime.gov.tw watch.stdtime.gov.tw |
|
| Thailand | NIMT - National Institute of Metrology (Thailand) | time1.nimt.or.th time2.nimt.or.th time3.nimt.or.th time4.nimt.or.th time5.nimt.or.th |
|
| Turkey | UME - Scientific and Technological Research Council | time.ume.tubitak.gov.tr | (unconfirmed) |
| Ukraine | NSC IM - National Scientific Center "Institute of Metrology", Kharkiv | 81.17.128.133 31.202.14.125 31.202.14.124 |
stratum 1, free access |
| United Kingdom | NPL - National Physical Laboratory | ntp1.npl.co.uk ntp2.npl.co.uk ntp3.npl.co.uk |
stratum 1 |
| USA | NIST - National Institute of Standards and Technology | time.nist.gov | full geographically distributed server list: http://tf.nist.gov/tf-cgi/servers.cgi |
| USA | USNO - U.S. Naval Observatory | tick.usno.navy.mil tock.usno.navy.mil |
only available in North America |
| Uzbekistan | UzNIM - Uzbek National Institute of Metrology | time.nim.uz | stratum 1 |
| Vietnam | VMI - Vietnam Metrology Institute | 14.232.244.11 | stratum 1 |
| Country | Operator | Servers | Notes |
|---|---|---|---|
| Sweden | Netnod - Swedish Distributed Time Service | ntp.se | disseminates Swedish official time, NTP + NTS |
| Brazil | NTP.br (NIC.br, traceable to the National Observatory) | a.st1.ntp.br b.st1.ntp.br c.st1.ntp.br d.st1.ntp.br gps.ntp.br |
- Greece (EIM) was removed: the 2025 edition reports "No Internet Time Service offered".
- Reachability spot-checked via sntp on 2026-07-21; ntp.inm.ro, time.saso.gov.sa, 14.232.244.11, master.ntp.mn and sltime.org did not answer from Western Europe at that time.
2026-07-21 — converted the per-country list into a per-institute table.
2026-07-21 — updated to the BIPM 2025 edition:
- Poland/AOS: vega.cbk.poznan.pl → ntp.cbk.poznan.pl
- Belgium/ORB: ntp1/ntp2.oma.be → ntp-public-1/ntp-public-2.oma.be
- Sweden/RISE: ntp1-4.sptime.se → ntp1-4.sp.se + nts1/nts2.ri.se
- South Korea: time.kriss.re.kr → ntp.kriss.re.kr (stratum 3 is the public one)
- Vietnam: 222.252.20.174 → 14.232.244.11
- Ukraine: ntp.metrology.kharkov.ua → three public IPs
- Colombia: fixed copy-paste error (had the Bosnian imbih.gov.ba hostnames)
- Norway: fixed institute name (Justervesenet = Norwegian Metrology Service, not "Correctional Service") and hostname typo
- Greece removed (EIM reports "No Internet Time Service offered" in 2025)
- Brazil/PADS-UFRJ removed (no longer in the report); ntp.br moved to the extras section
- UK: added ntp3.npl.co.uk; Poland/GUM: added tempus3; India: added time.nplindia.in; Netherlands: added ntp1.vsl.nl; Spain: added nts1.roa.es; Hong Kong: added stdtime.gov.hk + stdtime.hko.gov.hk; Russia: expanded VNIIFTRI to the full 12-server list
- New entries: Croatia, Jamaica, Mexico (link), New Zealand, Romania, Saudi Arabia, Serbia, Singapore, Sri Lanka, China/NTSC