Alt-Svc

HTTP response header

The Alt-Svc header is used to list alternate ways to reach this website

Header usage statistics

Alt-Svc response header information and usage statistics.

Websites using header Alt-Svc 465,014
Percentage of websites that use Alt-Svc header 3.99%
Total discovered header values 148
Header uses directives Yes
Header values are unique or random No
Most popular in the country United States of America

Alt-Svc Directives (12 total)

  • clear
  • h2
  • h3-24
  • h3-25
  • h3-q043
  • h3-q046
  • h3-q048
  • h3-q049
  • ma
  • persist
  • quic
  • v

Alt-Svc Directives

Alt-Svc directives value information and usage statistics

Directive Share Websites count Unique Values
ma 76.94% 357,771 13
quic 76.24% 354,521 20
v 76.24% 354,518 10
h3-q046 60.25% 280,167 11
h3-q043 60.25% 280,161 11
h3-25 41.84% 194,546 10
clear 3.07% 14,299 1
h3-24 1.90% 8,851 2
h2 <0.1% 81 30
h3-q048 <0.1% 39 2
h3-q049 <0.1% 26 2
persist <0.1% 24 2

Distribution by websites popularity

Alt-Svc detection in the top websites by popularity

Top 10k sites 824 websites
Top 100k sites 17,667 websites
Top 1m sites 60,062 websites

Websites utilizing Alt-Svc

List of websites that use Alt-Svc header

Domain Country Rank Contacts
fonts.googleapis.com United States of America 1
facebook.com United States of America 2
www.facebook.com United States of America 2
youtube.com United States of America 4
www.youtube.com United States of America 4
google.com United States of America 5
See full domain list

Geographical Distribution

Header usage distribution by websites across the globe.






Common header values

List of top common Alt-Svc header values

Header value Value prevalence
quic=":443"; ma=2592000; v="43,46", h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-25=":443"; ma=2592000, h3-27=":443"; ma=2592000 51.15%
h3-29=":443"; ma=2592000,h3-T051=":443"; ma=2592000,h3-Q050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43" 20.80%
quic=":443"; ma=86400; v="43,39" 18.08%
clear 3.84%
quic=":443"; ma=2592000; v="35,39,43,44" 1.15%
quic=":443"; ma=2592000; v="39,43,46", h3-Q039=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-23=":443"; ma=2592000, h3-24=":443"; ma=2592000 1.11%
quic=":443"; ma=2592000; v="43,46", h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-24=":443"; ma=2592000, h3-25=":443"; ma=2592000 1.01%
quic=":443"; ma=2592000; v="39,43,46", h3-22=":443"; ma=2592000 0.48%
quic=":443"; ma=2592000; v="39,43,46", h3-Q039=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-22=":443"; ma=2592000 0.31%
h3-27=":443"; ma=86400 0.27%
h3-27=":443"; ma=86400, h3-28=":443"; ma=86400, h3-29=":443"; ma=86400 0.25%
quic=":443"; ma=2592000; v="39,43,46,50", h3-Q039=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-23=":443"; ma=2592000, h3-24=":443"; ma=2592000 0.25%
h3-Q050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43" 0.23%
h3-29=":443"; ma=3600,h3-27=":443"; ma=3600 0.21%
quic=":443"; ma=2592000; v="35,37,38,39" 0.20%
quic=":443"; ma=2592000; v="39,43,46", h3-Q039=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-23=":443"; ma=2592000 0.13%
h3-29=":443"; ma=2592000 0.09%
quic=":443"; ma=2592000; v="43,46", h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q050=":443"; ma=2592000 0.08%
quic=":443"; ma=2592000; v="43,46", h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-29=":443"; ma=2592000, h3-32=":443"; ma=2592000 0.07%
quic=":443"; ma=2592000; v="43,46", h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-27=":443"; ma=2592000, h3-28=":443"; ma=2592000, h3-29=":443"; ma=2592000 0.05%