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 1,029,822
Percentage of websites that use Alt-Svc header 9.47%
Total discovered header values 140
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 78.96% 813,149 14
quic 30.77% 316,836 22
v 30.77% 316,833 8
h3-q043 29.71% 305,932 12
h3-q046 29.71% 305,932 12
h3-25 20.80% 214,209 11
clear 1.43% 14,697 1
h3-24 0.62% 6,424 2
h2 <0.1% 65 30
persist <0.1% 26 2
h3-q048 <0.1% 16 2
h3-q049 <0.1% 1 1

Distribution by websites popularity

Alt-Svc detection in the top websites by popularity

Top 10k sites 1,917 websites
Top 100k sites 25,792 websites
Top 1m sites 130,588 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
www.facebook.com Ireland 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
Flat price per report, subscription is not required.

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
h3-27=":443"; ma=86400, h3-28=":443"; ma=86400, h3-29=":443"; ma=86400 60.58%
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 25.04%
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" 9.96%
clear 1.76%
quic=":443"; ma=86400; v="43,39" 0.43%
quic=":443"; ma=2592000; v="35,39,43,44" 0.41%
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 0.33%
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 0.32%
quic=":443"; ma=2592000; v="39,43,46", h3-22=":443"; ma=2592000 0.17%
h3-Q050=":443"; ma=93600,quic=":443"; ma=93600; v="46,43" 0.17%
h3-Q050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43" 0.12%
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 0.10%
h3-29=":443"; ma=3600,h3-27=":443"; ma=3600 0.09%
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 0.09%
h3-34=":443"; ma=2592000, h3-29=":443"; ma=2592000, h3-27=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, quic=":443"; ma=2592000; v="43,46" 0.07%
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 0.05%
quic=":443"; ma=2592000; v="35,37,38,39" 0.05%
h3-32=":443"; ma=2592000, h3-29=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, quic=":443"; ma=2592000; v="43,46" 0.05%
h3-29=":443"; ma=2592000 0.04%
quic=":443"; ma=2592000; v="43,46", h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q050=":443"; ma=2592000 0.03%