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-svc9,917,803
Percentage of websites that use alt-svc header9.82%
Total discovered header values440
Header uses directivesYes
Header values are unique or randomNo
Most popular in the country US

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

DirectiveShareWebsites countUnique Values
ma99.32%9,850,48811
quic37.65%3,733,61721
v37.64%3,733,1288
h3-q04637.25%3,694,34612
h3-q04337.25%3,693,95312
h3-254.99%495,2506
clear0.61%60,8281
h3-240.46%45,3302
h2<0.1%7539
persist<0.1%3061
h3-q048<0.1%1852
h3-q049<0.1%972

Distribution by websites popularity

alt-svc detection in the top websites by popularity

Top 10k sites2,029 websites
Top 100k sites19,778 websites
Top 1m sites165,632 websites

Websites utilizing alt-svc

List of websites that use alt-svc header

See full domain list
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Geographical Distribution

Header usage distribution by websites across the globe.






Common header values

List of top common alt-svc header values

Header valueValue prevalence
h3=":443"; ma=86400, h3-29=":443"; ma=8640057.67%
h3=":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"24.85%
h3=":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="46,43"6.47%
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=25920004.90%
h3=":443"; ma=86400, h3-29=":443"; ma=86400, h3-28=":443"; ma=86400, h3-27=":443"; ma=864002.06%
h3=":443";ma=86400,h3-29=":443";ma=86400,h3-27=":443";ma=864001.35%
clear0.61%
h3=":443"; ma=2592000,h3-29=":443"; ma=25920000.48%
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"0.33%
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=25920000.28%
quic=":443"; ma=2592000; v="35,39,43,44"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=25920000.10%
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=25920000.08%
quic=":443"; ma=2592000; v="39,43,46", h3-22=":443"; ma=25920000.07%
quic=":443"; ma=2592000; v="39,43,46", h3-Q039=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-22=":443"; ma=25920000.05%
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=25920000.05%
h3-Q050=":443"; ma=93600,quic=":443"; ma=93600; v="46,43"0.04%
h3=":443"; ma=86400,h3-29=":443"; ma=864000.04%
h3-29=":443"0.04%
h3-23=":443"; ma=25920000.04%