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 642,649
Percentage of websites that use Alt-Svc header 5.62%
Total discovered header values 147
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
  • ma
  • quic
  • v
  • h2
  • persist
  • h3-25
  • h3-24
  • h3-q043
  • h3-q046
  • h3-q048
  • h3-q049

Alt-Svc Directives

Alt-Svc directives value information and usage statistics

Directive Share Websites count Unique Values
ma 14.20% 91,234 12
quic 13.68% 87,937 14
v 13.68% 87,935 9
clear 2.12% 13,638 1
h2 <0.1% 63 27
persist <0.1% 24 3
h3-25 <0.1% 3 2
h3-24 <0.1% 1 1
h3-q043 <0.1% 1 1
h3-q046 <0.1% 1 1
h3-q048 <0.1% 1 1
h3-q049 <0.1% 1 1

Distribution by websites popularity

Alt-Svc detection in the top websites by popularity

Top 10k sites 1,296 websites
Top 100k sites 21,050 websites
Top 1m sites 77,570 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 Ireland 2
youtube.com United States of America 4
google.com United States of America 5
www.youtube.com United States of America 14,442
www.facebook.com United States of America 22,750
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 34.71%
h3-27=":443"; ma=86400, h3-28=":443"; ma=86400, h3-29=":443"; ma=86400 25.69%
quic=":443"; ma=86400; v="43,39" 15.76%
h3-Q050=":443"; ma=2592000,h3-29=":443"; ma=2592000,h3-27=":443"; ma=2592000,h3-T051=":443"; ma=2592000,h3-T050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43" 12.43%
clear 2.57%
h3-29=":443"; ma=2592000,h3-27=":443"; ma=2592000,h3-T051=":443"; ma=2592000,h3-T050=":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" 1.84%
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 1.28%
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 1.09%
quic=":443"; ma=2592000; v="35,39,43,44" 1.07%
quic=":443"; ma=2592000; v="39,43,46", h3-22=":443"; ma=2592000 0.60%
h3-27=":443"; ma=86400 0.57%
h3-28=":443"; ma=2592000,h3-27=":443"; ma=2592000,h3-25=":443"; ma=2592000,h3-T050=":443"; ma=2592000,h3-Q050=":443"; ma=2592000,h3-Q049=":443"; ma=2592000,h3-Q048=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=25 0.46%
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 0.30%
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 0.30%
h3-Q050=":443"; ma=93600,h3-Q048=":443"; ma=93600,h3-Q046=":443"; ma=93600,h3-Q043=":443"; ma=93600,quic=":443"; ma=93600; v="50,48,46,43" 0.28%
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 0.18%
h3-27=":443"; ma=2592000,h3-25=":443"; ma=2592000,h3-T050=":443"; ma=2592000,h3-Q050=":443"; ma=2592000,h3-Q049=":443"; ma=2592000,h3-Q048=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43" 0.14%
h3-29=":443"; ma=3600,h3-27=":443"; ma=3600 0.14%
h3-Q050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43" 0.13%