<s>
QUIC	O
(	O
pronounced	O
"	O
quick	O
"	O
)	O
is	O
a	O
general-purpose	O
transport	B-Architecture
layer	I-Architecture
network	O
protocol	O
initially	O
designed	O
by	O
Jim	O
Roskind	O
at	O
Google	B-Application
,	O
implemented	O
,	O
and	O
deployed	O
in	O
2012	O
,	O
announced	O
publicly	O
in	O
2013	O
as	O
experimentation	O
broadened	O
,	O
and	O
described	O
at	O
an	O
IETF	O
meeting	O
.	O
</s>
<s>
QUIC	O
is	O
used	O
by	O
more	O
than	O
half	O
of	O
all	O
connections	O
from	O
the	O
Chrome	B-Application
web	I-Application
browser	I-Application
to	O
Google	B-Application
's	I-Application
servers	O
.	O
</s>
<s>
Microsoft	B-Application
Edge	I-Application
(	O
a	O
derivative	O
of	O
the	O
open-source	O
Chromium	B-Language
browser	I-Language
)	O
and	O
Firefox	B-Application
support	O
it	O
.	O
</s>
<s>
Safari	B-Application
implements	O
the	O
protocol	O
,	O
however	O
it	O
is	O
not	O
enabled	O
by	O
default	O
.	O
</s>
<s>
Although	O
its	O
name	O
was	O
initially	O
proposed	O
as	O
the	O
acronym	O
for	O
"	O
Quick	O
UDP	B-Protocol
Internet	O
Connections	O
"	O
,	O
IETF	O
's	O
use	O
of	O
the	O
word	O
QUIC	O
is	O
not	O
an	O
acronym	O
;	O
it	O
is	O
simply	O
the	O
name	O
of	O
the	O
protocol	O
.	O
</s>
<s>
QUIC	O
improves	O
performance	O
of	O
connection-oriented	O
web	B-Application
applications	I-Application
that	O
are	O
currently	O
using	O
TCP	B-Protocol
.	O
</s>
<s>
It	O
does	O
this	O
by	O
establishing	O
a	O
number	O
of	O
multiplexed	B-Architecture
connections	O
between	O
two	O
endpoints	O
using	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	B-Protocol
)	O
,	O
and	O
is	O
designed	O
to	O
obsolete	O
TCP	B-Protocol
at	O
the	O
transport	B-Architecture
layer	I-Architecture
for	O
many	O
applications	O
,	O
thus	O
earning	O
the	O
protocol	O
the	O
occasional	O
nickname	O
"	O
TCP/2	B-Protocol
"	O
.	O
</s>
<s>
QUIC	O
works	O
hand-in-hand	O
with	O
HTTP/2	B-Protocol
'	O
s	O
multiplexed	B-Architecture
connections	O
,	O
allowing	O
multiple	O
streams	O
of	O
data	O
to	O
reach	O
all	O
the	O
endpoints	O
independently	O
,	O
and	O
hence	O
independent	O
of	O
packet	B-Protocol
losses	I-Protocol
involving	O
other	O
streams	O
.	O
</s>
<s>
In	O
contrast	O
,	O
HTTP/2	B-Protocol
hosted	O
on	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
TCP	B-Protocol
)	O
can	O
suffer	O
head-of-line-blocking	B-Protocol
delays	O
of	O
all	O
multiplexed	B-Architecture
streams	O
if	O
any	O
of	O
the	O
TCP	B-Protocol
packets	B-Protocol
are	O
delayed	O
or	O
lost	O
.	O
</s>
<s>
QUIC	O
's	O
secondary	O
goals	O
include	O
reduced	O
connection	O
and	O
transport	O
latency	B-Protocol
,	O
and	O
bandwidth	O
estimation	O
in	O
each	O
direction	O
to	O
avoid	O
congestion	B-Protocol
.	O
</s>
<s>
It	O
also	O
moves	O
congestion	B-Protocol
control	O
algorithms	O
into	O
the	O
user	B-Operating_System
space	I-Operating_System
at	O
both	O
endpoints	O
,	O
rather	O
than	O
the	O
kernel	B-Operating_System
space	I-Operating_System
,	O
which	O
it	O
is	O
claimed	O
will	O
allow	O
these	O
algorithms	O
to	O
improve	O
more	O
rapidly	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
protocol	O
can	O
be	O
extended	O
with	O
forward	B-Error_Name
error	I-Error_Name
correction	I-Error_Name
(	O
FEC	O
)	O
to	O
further	O
improve	O
performance	O
when	O
errors	O
are	O
expected	O
,	O
and	O
this	O
is	O
seen	O
as	O
the	O
next	O
step	O
in	O
the	O
protocol	O
's	O
evolution	O
.	O
</s>
<s>
It	O
has	O
been	O
designed	O
to	O
avoid	O
protocol	B-Protocol
ossification	I-Protocol
so	O
that	O
it	O
remains	O
evolvable	O
,	O
unlike	O
TCP	B-Protocol
which	O
has	O
suffered	O
significant	O
ossification	O
.	O
</s>
<s>
In	O
October	O
2018	O
,	O
the	O
IETF	O
's	O
HTTP	B-Protocol
and	O
QUIC	O
Working	O
Groups	O
jointly	O
decided	O
to	O
call	O
the	O
HTTP	B-Protocol
mapping	O
over	O
QUIC	O
"	O
HTTP/3	B-Protocol
"	O
in	O
advance	O
of	O
making	O
it	O
a	O
worldwide	O
standard	O
.	O
</s>
<s>
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
,	O
or	O
TCP	B-Protocol
,	O
aims	O
to	O
provide	O
an	O
interface	O
for	O
sending	O
streams	O
of	O
data	O
between	O
two	O
endpoints	O
.	O
</s>
<s>
Data	O
is	O
handed	O
to	O
the	O
TCP	B-Protocol
system	O
,	O
which	O
ensures	O
the	O
data	O
makes	O
it	O
to	O
the	O
other	O
end	O
in	O
exactly	O
the	O
same	O
form	O
,	O
or	O
the	O
connection	O
will	O
indicate	O
that	O
an	O
error	O
condition	O
exists	O
.	O
</s>
<s>
To	O
do	O
this	O
,	O
TCP	B-Protocol
breaks	O
up	O
the	O
data	O
into	O
network	B-Protocol
packets	I-Protocol
and	O
adds	O
small	O
amounts	O
of	O
data	O
to	O
each	O
packet	B-Protocol
.	O
</s>
<s>
This	O
additional	O
data	O
includes	O
a	O
sequence	B-Protocol
number	I-Protocol
that	O
is	O
used	O
to	O
detect	O
packets	B-Protocol
that	O
are	O
lost	O
or	O
arrive	O
out	O
of	O
order	O
,	O
and	O
a	O
checksum	B-Algorithm
that	O
allows	O
the	O
errors	O
within	O
packet	B-Protocol
data	I-Protocol
to	O
be	O
detected	O
.	O
</s>
<s>
When	O
either	O
problem	O
occurs	O
,	O
TCP	B-Protocol
uses	O
automatic	B-Error_Name
repeat	I-Error_Name
request	I-Error_Name
(	O
ARQ	O
)	O
to	O
tell	O
the	O
sender	O
to	O
re-send	O
the	O
lost	O
or	O
damaged	O
packet	B-Protocol
.	O
</s>
<s>
In	O
most	O
implementations	O
,	O
TCP	B-Protocol
will	O
see	O
any	O
error	O
on	O
a	O
connection	O
as	O
a	O
blocking	O
operation	O
,	O
stopping	O
further	O
transfers	O
until	O
the	O
error	O
is	O
resolved	O
or	O
the	O
connection	O
is	O
considered	O
failed	O
.	O
</s>
<s>
If	O
a	O
single	O
connection	O
is	O
being	O
used	O
to	O
send	O
multiple	O
streams	O
of	O
data	O
,	O
as	O
is	O
the	O
case	O
in	O
the	O
HTTP/2	B-Protocol
protocol	O
,	O
all	O
of	O
these	O
streams	O
are	O
blocked	O
although	O
only	O
one	O
of	O
them	O
might	O
have	O
a	O
problem	O
.	O
</s>
<s>
This	O
phenomenon	O
is	O
known	O
as	O
head-of-line	B-Protocol
blocking	I-Protocol
.	O
</s>
<s>
As	O
the	O
TCP	B-Protocol
system	O
is	O
designed	O
to	O
look	O
like	O
a	O
"	O
data	O
pipe	O
"	O
,	O
or	O
stream	O
,	O
it	O
deliberately	O
contains	O
little	O
understanding	O
of	O
the	O
data	O
it	O
transmits	O
.	O
</s>
<s>
If	O
that	O
data	O
has	O
additional	O
requirements	O
,	O
like	O
encryption	O
using	O
TLS	B-Protocol
,	O
this	O
must	O
be	O
set	O
up	O
by	O
systems	O
running	O
on	O
top	O
of	O
TCP	B-Protocol
,	O
using	O
TCP	B-Protocol
to	O
communicate	O
with	O
similar	O
software	O
on	O
the	O
other	O
end	O
of	O
the	O
connection	O
.	O
</s>
<s>
Each	O
of	O
these	O
sorts	O
of	O
setup	O
tasks	O
requires	O
its	O
own	O
handshake	B-Protocol
process	I-Protocol
.	O
</s>
<s>
Due	O
to	O
the	O
inherent	O
latency	B-Protocol
of	O
long-distance	O
communications	O
,	O
this	O
can	O
add	O
significant	O
overhead	O
to	O
the	O
overall	O
transmission	O
.	O
</s>
<s>
TCP	B-Protocol
has	O
suffered	O
from	O
protocol	B-Protocol
ossification	I-Protocol
,	O
due	O
to	O
its	O
wire	O
image	O
being	O
in	O
cleartext	O
and	O
hence	O
visible	O
to	O
and	O
malleable	O
by	O
middleboxes	O
.	O
</s>
<s>
One	O
measurement	O
found	O
that	O
a	O
third	O
of	O
paths	O
across	O
the	O
Internet	O
encounter	O
at	O
least	O
one	O
intermediary	O
that	O
modifies	O
TCP	B-Protocol
metadata	O
,	O
and	O
6.5	O
%	O
of	O
paths	O
encounter	O
harmful	O
ossifying	O
effects	O
from	O
intermediaries	O
.	O
</s>
<s>
Extensions	O
to	O
TCP	B-Protocol
have	O
been	O
affected	O
:	O
the	O
design	O
of	O
MPTCP	B-Protocol
was	O
constrained	O
by	O
middlebox	O
behaviour	O
,	O
and	O
the	O
deployment	O
of	O
TCP	B-Protocol
Fast	I-Protocol
Open	I-Protocol
has	O
been	O
likewise	O
hindered	O
.	O
</s>
<s>
QUIC	O
aims	O
to	O
be	O
nearly	O
equivalent	O
to	O
a	O
TCP	B-Protocol
connection	O
but	O
with	O
much-reduced	O
latency	B-Protocol
.	O
</s>
<s>
It	O
does	O
this	O
primarily	O
through	O
two	O
changes	O
that	O
rely	O
on	O
the	O
understanding	O
of	O
the	O
behaviour	O
of	O
HTTP	B-Protocol
traffic	O
.	O
</s>
<s>
As	O
most	O
HTTP	B-Protocol
connections	O
will	O
demand	O
TLS	B-Protocol
,	O
QUIC	O
makes	O
the	O
exchange	O
of	O
setup	O
keys	O
and	O
supported	O
protocols	O
part	O
of	O
the	O
initial	O
handshake	B-Protocol
process	I-Protocol
.	O
</s>
<s>
When	O
a	O
client	O
opens	O
a	O
connection	O
,	O
the	O
response	O
packet	B-Protocol
includes	O
the	O
data	O
needed	O
for	O
future	O
packets	B-Protocol
to	O
use	O
encryption	O
.	O
</s>
<s>
This	O
eliminates	O
the	O
need	O
to	O
set	O
up	O
the	O
TCP	B-Protocol
connection	O
and	O
then	O
negotiate	O
the	O
security	O
protocol	O
via	O
additional	O
packets	B-Protocol
.	O
</s>
<s>
The	O
second	O
change	O
is	O
to	O
use	O
UDP	B-Protocol
rather	O
than	O
TCP	B-Protocol
as	O
its	O
basis	O
,	O
which	O
does	O
not	O
include	O
loss	B-Protocol
recovery	O
.	O
</s>
<s>
Instead	O
,	O
each	O
QUIC	O
stream	O
is	O
separately	O
flow	O
controlled	O
and	O
lost	O
data	O
is	O
retransmitted	O
at	O
the	O
level	O
of	O
QUIC	O
,	O
not	O
UDP	B-Protocol
.	O
</s>
<s>
This	O
means	O
that	O
if	O
an	O
error	O
occurs	O
in	O
one	O
stream	O
,	O
like	O
the	O
favicon	O
example	O
above	O
,	O
the	O
protocol	B-Protocol
stack	I-Protocol
can	O
continue	O
servicing	O
other	O
streams	O
independently	O
.	O
</s>
<s>
This	O
can	O
be	O
very	O
useful	O
in	O
improving	O
performance	O
on	O
error-prone	O
links	O
,	O
as	O
in	O
most	O
cases	O
considerable	O
additional	O
data	O
may	O
be	O
received	O
before	O
TCP	B-Protocol
notices	O
a	O
packet	B-Protocol
is	O
missing	O
or	O
broken	O
,	O
and	O
all	O
of	O
this	O
data	O
is	O
blocked	O
or	O
even	O
flushed	O
while	O
the	O
error	O
is	O
corrected	O
.	O
</s>
<s>
In	O
QUIC	O
,	O
this	O
data	O
is	O
free	O
to	O
be	O
processed	O
while	O
the	O
single	O
multiplexed	B-Architecture
stream	O
is	O
repaired	O
.	O
</s>
<s>
QUIC	O
also	O
includes	O
a	O
number	O
of	O
other	O
changes	O
that	O
also	O
improve	O
overall	O
latency	B-Protocol
and	O
throughput	O
.	O
</s>
<s>
For	O
instance	O
,	O
the	O
packets	B-Protocol
are	O
encrypted	O
individually	O
,	O
so	O
that	O
they	O
do	O
not	O
result	O
in	O
the	O
encrypted	O
data	O
waiting	O
for	O
partial	O
packets	B-Protocol
.	O
</s>
<s>
This	O
is	O
not	O
generally	O
possible	O
under	O
TCP	B-Protocol
,	O
where	O
the	O
encryption	O
records	O
are	O
in	O
a	O
bytestream	O
and	O
the	O
protocol	B-Protocol
stack	I-Protocol
is	O
unaware	O
of	O
higher-layer	O
boundaries	O
within	O
this	O
stream	O
.	O
</s>
<s>
These	O
can	O
be	O
negotiated	O
by	O
the	O
layers	O
running	O
on	O
top	O
,	O
but	O
QUIC	O
aims	O
to	O
do	O
all	O
of	O
this	O
in	O
a	O
single	O
handshake	B-Protocol
process	I-Protocol
.	O
</s>
<s>
Another	O
goal	O
of	O
the	O
QUIC	O
system	O
was	O
to	O
improve	O
performance	O
during	O
network-switch	O
events	O
,	O
like	O
what	O
happens	O
when	O
a	O
user	O
of	O
a	O
mobile	O
device	O
moves	O
from	O
a	O
local	O
WiFi	B-Application
hotspot	I-Application
to	O
a	O
mobile	O
network	O
.	O
</s>
<s>
When	O
this	O
occurs	O
on	O
TCP	B-Protocol
,	O
a	O
lengthy	O
process	O
starts	O
where	O
every	O
existing	O
connection	O
times	O
out	O
one-by-one	O
and	O
is	O
then	O
re-established	O
on	O
demand	O
.	O
</s>
<s>
This	O
allows	O
the	O
connection	O
to	O
be	O
re-established	O
simply	O
by	O
sending	O
a	O
packet	B-Protocol
,	O
which	O
always	O
contains	O
this	O
ID	O
,	O
as	O
the	O
original	O
connection	O
ID	O
will	O
still	O
be	O
valid	O
even	O
if	O
the	O
user	O
's	O
IP	B-Protocol
address	I-Protocol
changes	O
.	O
</s>
<s>
QUIC	O
can	O
be	O
implemented	O
in	O
the	O
application-space	O
,	O
as	O
opposed	O
to	O
being	O
in	O
the	O
operating	B-Operating_System
system	I-Operating_System
kernel	I-Operating_System
.	O
</s>
<s>
This	O
generally	O
invokes	O
additional	O
overhead	O
due	O
to	O
context	B-Operating_System
switches	I-Operating_System
as	O
data	O
is	O
moved	O
between	O
applications	O
.	O
</s>
<s>
However	O
,	O
in	O
the	O
case	O
of	O
QUIC	O
,	O
the	O
protocol	B-Protocol
stack	I-Protocol
is	O
intended	O
to	O
be	O
used	O
by	O
a	O
single	O
application	O
,	O
with	O
each	O
application	O
using	O
QUIC	O
having	O
its	O
own	O
connections	O
hosted	O
on	O
UDP	B-Protocol
.	O
</s>
<s>
Ultimately	O
the	O
difference	O
could	O
be	O
very	O
small	O
because	O
much	O
of	O
the	O
overall	O
HTTP/2	B-Protocol
stack	O
is	O
already	O
in	O
the	O
applications	O
(	O
or	O
their	O
libraries	O
,	O
more	O
commonly	O
)	O
.	O
</s>
<s>
Placing	O
the	O
remaining	O
parts	O
in	O
those	O
libraries	O
,	O
essentially	O
the	O
error	O
correction	O
,	O
has	O
little	O
effect	O
on	O
the	O
HTTP/2	B-Protocol
stack	O
's	O
size	O
or	O
overall	O
complexity	O
.	O
</s>
<s>
This	O
organization	O
allows	O
future	O
changes	O
to	O
be	O
made	O
more	O
easily	O
as	O
it	O
does	O
not	O
require	O
changes	O
to	O
the	O
kernel	B-Operating_System
for	O
updates	O
.	O
</s>
<s>
One	O
of	O
QUIC	O
's	O
longer-term	O
goals	O
is	O
to	O
add	O
new	O
systems	O
for	O
forward	B-Error_Name
error	I-Error_Name
correction	I-Error_Name
(	O
FEC	O
)	O
and	O
improved	O
congestion	B-Protocol
control	O
.	O
</s>
<s>
One	O
concern	O
about	O
the	O
move	O
from	O
TCP	B-Protocol
to	O
UDP	B-Protocol
is	O
that	O
TCP	B-Protocol
is	O
widely	O
adopted	O
and	O
many	O
of	O
the	O
"	O
middleboxes	O
"	O
in	O
the	O
internet	O
infrastructure	O
are	O
tuned	O
for	O
TCP	B-Protocol
and	O
rate-limit	O
or	O
even	O
block	O
UDP	B-Protocol
.	O
</s>
<s>
Google	B-Application
carried	O
out	O
a	O
number	O
of	O
exploratory	O
experiments	O
to	O
characterize	O
this	O
and	O
found	O
that	O
only	O
a	O
small	O
number	O
of	O
connections	O
were	O
blocked	O
in	O
this	O
manner	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
use	O
of	O
a	O
rapid	O
fallback-to-TCP	O
system	O
;	O
Chromium	B-Language
's	O
network	B-Protocol
stack	I-Protocol
opens	O
both	O
a	O
QUIC	O
and	O
traditional	O
TCP	B-Protocol
connection	O
at	O
the	O
same	O
time	O
,	O
which	O
allows	O
it	O
to	O
fall	O
back	O
with	O
negligible	O
latency	B-Protocol
.	O
</s>
<s>
QUIC	O
has	O
been	O
specifically	O
designed	O
to	O
be	O
deployable	O
,	O
evolvable	O
and	O
to	O
have	O
anti-ossification	O
properties	O
;	O
it	O
is	O
the	O
first	O
IETF	O
transport	B-Architecture
protocol	I-Architecture
to	O
deliberately	O
minimise	O
its	O
wire	O
image	O
for	O
these	O
ends	O
.	O
</s>
<s>
The	O
protocol	O
that	O
was	O
created	O
by	O
Google	B-Application
and	O
taken	O
to	O
the	O
IETF	O
under	O
the	O
name	O
QUIC	O
(	O
already	O
in	O
2012	O
around	O
QUIC	O
version	O
20	O
)	O
is	O
quite	O
different	O
from	O
the	O
QUIC	O
that	O
has	O
continued	O
to	O
evolve	O
and	O
be	O
refined	O
within	O
the	O
IETF	O
.	O
</s>
<s>
The	O
original	O
Google	B-Application
QUIC	O
was	O
designed	O
to	O
be	O
a	O
general	O
purpose	O
protocol	O
,	O
though	O
it	O
was	O
initially	O
deployed	O
as	O
a	O
protocol	O
to	O
support	O
HTTP(S )	O
in	O
Chromium	B-Language
.	O
</s>
<s>
The	O
current	O
evolution	O
of	O
the	O
IETF	O
QUIC	O
protocol	O
is	O
a	O
general	O
purpose	O
transport	B-Architecture
protocol	I-Architecture
.	O
</s>
<s>
Chromium	B-Language
developers	O
continued	O
to	O
track	O
the	O
evolution	O
of	O
IETF	O
QUIC	O
's	O
standardization	O
efforts	O
to	O
adopt	O
and	O
fully	O
comply	O
with	O
the	O
most	O
recent	O
internet	O
standards	O
for	O
QUIC	O
in	O
Chromium	B-Language
.	O
</s>
<s>
QUIC	O
developed	O
with	O
HTTP	B-Protocol
in	O
mind	O
,	O
and	O
HTTP/3	B-Protocol
was	O
its	O
first	O
application	O
.	O
</s>
<s>
DNS-over-QUIC	O
is	O
an	O
application	O
of	O
QUIC	O
to	O
name	O
resolution	O
,	O
providing	O
security	O
for	O
data	O
transferred	O
between	O
resolvers	O
similar	O
to	O
DNS-over-TLS	B-Protocol
.	O
</s>
<s>
The	O
IETF	O
is	O
also	O
developing	O
an	O
application	O
of	O
QUIC	O
to	O
make	O
a	O
secure	O
tunnelling	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
The	O
QUIC	O
code	O
was	O
experimentally	O
developed	O
in	O
Google	B-Application
Chrome	I-Application
starting	O
in	O
2012	O
,	O
and	O
was	O
announced	O
as	O
part	O
of	O
Chromium	B-Language
version	O
29	O
(	O
released	O
on	O
August	O
20	O
,	O
2013	O
)	O
.	O
</s>
<s>
It	O
is	O
currently	O
enabled	O
by	O
default	O
in	O
Chromium	B-Language
and	O
Chrome	B-Application
.	O
</s>
<s>
Support	O
in	O
Firefox	B-Application
arrived	O
in	O
May	O
2021	O
.	O
</s>
<s>
Apple	O
added	O
experimental	O
support	O
in	O
the	O
WebKit	B-Language
engine	I-Language
through	O
the	O
Safari	B-Application
Technology	O
Preview	O
104	O
in	O
April	O
2020	O
.	O
</s>
<s>
Official	O
support	O
was	O
added	O
in	O
Safari	B-Application
14	O
,	O
included	O
in	O
macOS	B-Operating_System
Big	I-Operating_System
Sur	I-Operating_System
and	O
iOS	B-Operating_System
14	I-Operating_System
,	O
but	O
the	O
feature	O
must	O
be	O
turned	O
on	O
manually	O
.	O
</s>
<s>
The	O
cronet	O
library	O
for	O
QUIC	O
and	O
other	O
protocols	O
is	O
available	O
to	O
Android	O
applications	O
as	O
a	O
module	O
loadable	O
via	O
Google	B-Application
Play	I-Application
Services	I-Application
.	O
</s>
<s>
cURL	B-Language
7.66	O
,	O
released	O
11	O
September	O
2019	O
,	O
supports	O
HTTP/3	B-Protocol
(	O
and	O
thus	O
QUIC	O
)	O
.	O
</s>
<s>
In	O
October	O
2020	O
,	O
Facebook	B-Application
announced	O
that	O
it	O
has	O
successfully	O
migrated	O
its	O
apps	O
,	O
including	O
Instagram	B-Application
,	O
and	O
server	O
infrastructure	O
to	O
QUIC	O
,	O
with	O
already	O
75%	O
of	O
its	O
Internet	O
traffic	O
using	O
QUIC	O
.	O
</s>
<s>
All	O
mobile	O
apps	O
from	O
Google	B-Application
support	I-Application
QUIC	O
,	O
including	O
YouTube	B-General_Concept
and	O
Gmail	B-Application
.	O
</s>
<s>
Uber	B-Application
's	O
mobile	O
app	O
also	O
uses	O
QUIC	O
.	O
</s>
<s>
Google	B-Application
servers	O
support	O
QUIC	O
and	O
Google	B-Application
has	O
published	O
a	O
prototype	O
server	O
.	O
</s>
<s>
Akamai	B-Application
Technologies	I-Application
has	O
been	O
supporting	O
QUIC	O
since	O
July	O
2016	O
.	O
</s>
<s>
A	O
Go	B-Application
implementation	O
called	O
quic-go	O
is	O
also	O
available	O
,	O
and	O
powers	O
experimental	O
QUIC	O
support	O
in	O
the	O
Caddy	B-Language
server	I-Language
.	O
</s>
<s>
On	O
July	O
11	O
,	O
2017	O
,	O
LiteSpeed	B-Protocol
Technologies	I-Protocol
officially	O
began	O
supporting	O
QUIC	O
in	O
their	O
load	O
balancer	O
(	O
WebADC	O
)	O
and	O
LiteSpeed	B-Protocol
Web	I-Protocol
Server	I-Protocol
products	O
.	O
</s>
<s>
,	O
88.6	O
%	O
of	O
QUIC	O
websites	O
used	O
LiteSpeed	B-Protocol
and	O
10.8	O
%	O
used	O
Nginx	B-Operating_System
.	O
</s>
<s>
Although	O
at	O
first	O
only	O
Google	B-Application
servers	O
supported	O
HTTP-over-QUIC	O
connections	O
,	O
Facebook	B-Application
also	O
launched	O
the	O
technology	O
in	O
2018	O
,	O
and	O
Cloudflare	B-Application
has	O
been	O
offering	O
QUIC	O
support	O
on	O
a	O
beta	O
basis	O
since	O
2018	O
.	O
,	O
8.9	O
%	O
of	O
all	O
websites	O
use	O
QUIC	O
,	O
up	O
from	O
5%	O
in	O
March	O
2021	O
.	O
</s>
<s>
Microsoft	B-Device
Windows	I-Device
Server	I-Device
2022	I-Device
supports	O
both	O
HTTP/3	B-Protocol
and	O
SMB	O
over	O
QUIC	O
protocols	O
via	O
MsQuic	B-Language
.	O
</s>
<s>
The	O
Application	O
Delivery	O
Controller	O
of	O
Citrix	B-Application
(	O
Citrix	B-Application
ADC	O
,	O
NetScaler	O
)	O
can	O
function	O
as	O
a	O
QUIC	O
proxy	O
since	O
version	O
13	O
.	O
</s>
<s>
In	O
addition	O
,	O
there	O
are	O
several	O
stale	O
community	O
projects	O
:	O
libquic	O
was	O
created	O
by	O
extracting	O
the	O
Chromium	B-Language
implementation	O
of	O
QUIC	O
and	O
modifying	O
it	O
to	O
minimize	O
dependency	O
requirements	O
,	O
and	O
goquic	O
provides	O
Go	B-Application
bindings	O
of	O
libquic	O
.	O
</s>
<s>
Finally	O
,	O
quic-reverse-proxy	O
is	O
a	O
Docker	B-Language
image	I-Language
that	O
acts	O
as	O
a	O
reverse	B-General_Concept
proxy	I-General_Concept
server	O
,	O
translating	O
QUIC	O
requests	O
into	O
plain	O
HTTP	B-Protocol
that	O
can	O
be	O
understood	O
by	O
the	O
origin	O
server	O
.	O
</s>
<s>
.NET	B-Application
5	I-Application
introduces	O
experimental	O
support	O
for	O
QUIC	O
using	O
the	O
MsQuic	B-Language
library	O
.	O
</s>
<s>
+The	O
following	O
implementations	O
of	O
QUIC	O
or	O
gQUIC	O
are	O
available	O
in	O
source	O
form:ImplementationLicenseLanguageDescriptionChromium	O
C++	O
This	O
is	O
the	O
source	O
code	O
of	O
the	O
Chrome	B-Application
web	I-Application
browser	I-Application
and	O
the	O
reference	O
gQUIC	O
implementation	O
.	O
</s>
<s>
This	O
version	O
is	O
also	O
the	O
basis	O
of	O
LINE	B-Application
's	O
stellite	O
and	O
Google	B-Application
's	I-Application
cronet.MsQuic	O
CA	O
cross	O
platform	O
QUIC	O
implementation	O
from	O
Microsoft	O
designed	O
to	O
be	O
a	O
general	O
purpose	O
QUIC	O
library	O
.	O
</s>
<s>
Used	O
in	O
Windows	O
and	O
cross	O
platform	O
by	O
.NET	B-Application
.	O
</s>
<s>
Rust	O
and	O
C#	O
interop	O
layers	O
available.QUIC	O
Library	O
(	O
mvfst	O
)	O
C++mvfst	O
(	O
Pronounced	O
move	O
fast	O
)	O
is	O
a	O
client	O
and	O
server	O
implementation	O
of	O
IETF	O
QUIC	O
protocol	O
in	O
C++	O
by	O
Facebook.LiteSpeed	O
QUIC	O
Library	O
(	O
lsquic	O
)	O
CThis	O
is	O
the	O
QUIC	O
and	O
HTTP/3	B-Protocol
implementation	O
used	O
by	O
LiteSpeed	B-Protocol
Web	I-Protocol
Server	I-Protocol
and	O
OpenLiteSpeed.ngtcp2	O
CThis	O
is	O
a	O
QUIC	O
library	O
that	O
's	O
crypto	O
library	O
agnostic	O
and	O
works	O
with	O
OpenSSL	O
or	O
GnuTLS	O
.	O
</s>
<s>
For	O
HTTP/3	B-Protocol
,	O
it	O
needs	O
a	O
separate	O
library	O
like	O
nghttp3.Quiche	O
RustSocket-agnostic	O
and	O
exposes	O
a	O
C	O
API	O
for	O
use	O
in	O
C/C	O
++	O
applications.quicly	O
CThis	O
library	O
is	O
the	O
QUIC	O
implementation	O
for	O
the	O
H2O	O
web	O
server.quic-go	O
GoThis	O
library	O
provides	O
QUIC	O
support	O
for	O
golang	B-Application
applications	O
.	O
</s>
<s>
 [ QuicSec ] 	O
adds	O
HTTP3	B-Protocol
support	O
to	O
existing	O
apps	O
with	O
optional	O
mTLS	O
and	O
observability	O
.	O
</s>
<s>
Quic-go	O
is	O
used	O
by	O
various	O
golang	B-Application
apps	O
like	O
the	O
Caddy	O
web	O
server.Quinn	O
RustNeqo	O
RustThis	O
implementation	O
from	O
Mozilla	B-Operating_System
is	O
planned	O
to	O
be	O
integrated	O
in	O
Necko	O
,	O
a	O
network	O
library	O
used	O
in	O
the	O
Firefox	B-Application
web	O
browseraioquic	O
PythonThis	O
library	O
features	O
an	O
I/O	O
-free	O
API	O
suitable	O
for	O
embedding	O
in	O
both	O
clients	O
and	O
servers.picoquic	O
CA	O
minimal	O
implementation	O
of	O
QUIC	O
aligned	O
with	O
the	O
IETF	O
specificationspquic	O
CAn	O
extensible	O
QUIC	O
implementation	O
that	O
includes	O
an	O
eBPF	B-Protocol
virtual	O
machine	O
that	O
is	O
able	O
to	O
dynamically	O
load	O
extensions	O
as	O
pluginsQUANT	O
CQuant	O
supports	O
traditional	O
POSIX	O
platforms	O
(	O
Linux	O
,	O
MacOS	O
,	O
FreeBSD	O
,	O
etc	O
.	O
)	O
</s>
