<s>
Greasemonkey	B-Operating_System
is	O
a	O
userscript	B-Language
manager	I-Language
made	O
available	O
as	O
a	O
Mozilla	B-Application
Firefox	I-Application
extension	B-Operating_System
.	O
</s>
<s>
It	O
enables	O
users	O
to	O
install	O
scripts	B-Language
that	O
make	O
on-the-fly	O
changes	O
to	O
web	O
page	O
content	O
after	O
or	O
before	O
the	O
page	O
is	O
loaded	O
in	O
the	O
browser	O
(	O
also	O
known	O
as	O
augmented	B-Protocol
browsing	I-Protocol
)	O
.	O
</s>
<s>
Greasemonkey	B-Operating_System
can	O
be	O
used	O
for	O
customizing	O
page	O
appearance	O
,	O
adding	O
new	O
functions	O
to	O
web	O
pages	O
(	O
for	O
example	O
,	O
embedding	O
price	O
comparisons	O
within	O
shopping	O
sites	O
)	O
,	O
fixing	O
rendering	O
bugs	O
,	O
combining	O
data	O
from	O
multiple	O
web	O
pages	O
,	O
and	O
numerous	O
other	O
purposes	O
.	O
</s>
<s>
The	O
Greasemonkey	B-Operating_System
project	O
began	O
28	O
November	O
2004	O
,	O
written	O
by	O
Aaron	O
Boodman	O
.	O
</s>
<s>
Boodman	O
was	O
inspired	O
to	O
write	O
Greasemonkey	B-Operating_System
after	O
looking	O
at	O
a	O
Firefox	B-Operating_System
extension	I-Operating_System
designed	O
to	O
clean	O
up	O
the	O
interface	O
of	O
AllMusic	O
,	O
written	O
by	O
Adrian	O
Holovaty	O
,	O
who	O
later	O
became	O
a	O
userscript	O
developer	O
.	O
</s>
<s>
By	O
May	O
2005	O
,	O
there	O
were	O
approximately	O
60	O
general	O
and	O
115	O
site-specific	O
userscripts	O
distributed	O
for	O
Greasemonkey	B-Operating_System
.	O
</s>
<s>
In	O
July	O
2005	O
,	O
serious	O
vulnerabilities	O
were	O
found	O
in	O
Greasemonkey	B-Operating_System
by	O
Mark	O
Pilgrim	O
,	O
and	O
fixed	O
in	O
the	O
3.5	O
version	O
of	O
Greasemonkey	B-Operating_System
.	O
</s>
<s>
During	O
this	O
time	O
,	O
a	O
Greasemonkey	B-Operating_System
compiler	O
was	O
also	O
developed	O
for	O
converting	O
a	O
userscript	O
into	O
a	O
standalone	O
Firefox	B-Operating_System
extension	I-Operating_System
.	O
</s>
<s>
Greasemonkey	B-Operating_System
was	O
initially	O
met	O
with	O
complaints	O
by	O
publishers	O
for	O
its	O
ability	O
to	O
block	O
ads	O
.	O
</s>
<s>
However	O
,	O
this	O
criticism	O
shifted	O
its	O
focus	O
to	O
other	O
addons	B-Operating_System
starting	O
with	O
the	O
2006	O
release	O
of	O
Adblock	B-Application
Plus	I-Application
.	O
</s>
<s>
To	O
accommodate	O
the	O
growing	O
number	O
of	O
scripts	B-Language
,	O
userscripts.org	O
was	O
founded	O
by	O
Britt	O
Selvitelle	O
and	O
other	O
members	O
of	O
the	O
Greasemonkey	B-Operating_System
community	O
in	O
late	O
2005	O
.	O
</s>
<s>
As	O
the	O
main	O
script	O
repository	O
listed	O
on	O
Greasemonkey	B-Operating_System
's	O
official	O
site	O
,	O
userscripts.org	O
accumulated	O
thousands	O
of	O
scripts	B-Language
per	O
year	O
.	O
</s>
<s>
Prior	O
to	O
this	O
,	O
many	O
of	O
the	O
"	O
most	O
popular	O
scripts	B-Language
"	O
as	O
listed	O
by	O
the	O
site	O
had	O
nominal	O
install	O
counts	O
of	O
zero	O
.	O
</s>
<s>
Over	O
the	O
following	O
year	O
spam	O
scripts	B-Language
became	O
more	O
common	O
,	O
server	O
downtime	O
increased	O
and	O
the	O
install	O
count	O
bug	O
remained	O
.	O
</s>
<s>
With	O
no	O
further	O
communication	O
by	O
Andrews	O
,	O
userscript	O
writers	O
described	O
the	O
site	O
as	O
neglected	O
and	O
the	O
official	O
Greasemonkey	B-Operating_System
site	O
removed	O
its	O
front	O
page	O
link	O
.	O
</s>
<s>
In	O
response	O
,	O
script	O
writers	O
and	O
other	O
developers	O
began	O
working	O
on	O
the	O
fork	B-Application
"	O
openuserjs.org	O
 "	O
,	O
and	O
later	O
greasyfork.org,	O
as	O
an	O
immediate	O
replacement	O
.	O
</s>
<s>
Most	O
of	O
its	O
scripts	B-Language
were	O
backed	O
up	O
to	O
the	O
static	O
mirror	O
userscripts-mirror.org	O
where	O
they	O
can	O
now	O
be	O
found	O
.	O
</s>
<s>
Greasemonkey	B-Operating_System
user	O
scripts	B-Language
are	O
written	O
in	O
JavaScript	B-Language
and	O
manipulate	O
the	O
contents	O
of	O
a	O
web	O
page	O
using	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
interface	O
.	O
</s>
<s>
Scripts	B-Language
are	O
generally	O
written	O
to	O
be	O
either	O
page-specific	O
or	O
domain-specific	O
(	O
applying	O
to	O
all	O
pages	O
within	O
a	O
domain	O
)	O
but	O
may	O
also	O
be	O
tagged	O
to	O
apply	O
to	O
all	O
domains	O
for	O
global	O
browser	O
enhancements	O
.	O
</s>
<s>
Users	O
of	O
Greasemonkey	B-Operating_System
can	O
write	O
or	O
download	O
scripts	B-Language
and	O
save	O
them	O
to	O
their	O
own	O
personal	O
library	O
.	O
</s>
<s>
When	O
users	O
visit	O
a	O
website	O
matching	O
a	O
script	O
in	O
their	O
personal	O
script	O
library	O
,	O
Greasemonkey	B-Operating_System
invokes	O
the	O
relevant	O
scripts	B-Language
.	O
</s>
<s>
Greasemonkey	B-Operating_System
scripts	B-Language
can	O
modify	O
a	O
webpage	O
in	O
any	O
way	O
that	O
JavaScript	B-Language
allows	O
,	O
with	O
certain	O
Greasemonkey	B-Operating_System
security	O
restrictions	O
.	O
</s>
<s>
Scripts	B-Language
can	O
also	O
access	O
other	O
web	O
pages	O
and	O
web	O
services	O
via	O
a	O
non-domain-restricted	B-Protocol
XMLHTTP	B-Protocol
request	O
,	O
allowing	O
external	O
content	O
to	O
be	O
merged	O
with	O
the	O
original	O
page	O
content	O
.	O
</s>
<s>
Scripts	B-Language
are	O
named	O
somename.user.js	O
,	O
and	O
Greasemonkey	B-Operating_System
offers	O
to	O
install	O
any	O
such	O
script	O
when	O
a	O
URL	O
ending	O
in	O
that	O
suffix	O
is	O
requested	O
.	O
</s>
<s>
Greasemonkey	B-Operating_System
scripts	B-Language
contain	O
metadata	O
which	O
specifies	O
the	O
name	O
of	O
the	O
script	O
,	O
a	O
description	O
,	O
resources	O
required	O
by	O
the	O
script	O
,	O
a	O
namespace	O
URL	O
used	O
to	O
differentiate	O
identically	O
named	O
scripts	B-Language
,	O
and	O
URL	O
patterns	O
for	O
which	O
the	O
script	O
is	O
intended	O
to	O
be	O
invoked	O
or	O
not	O
.	O
</s>
<s>
Writing	O
a	O
Greasemonkey	B-Operating_System
script	O
is	O
similar	O
to	O
writing	O
JavaScript	B-Language
for	O
a	O
web	O
page	O
,	O
with	O
some	O
additional	O
allowances	O
such	O
as	O
cross-site	O
XMLHttpRequests	B-Protocol
.	O
</s>
<s>
Compared	O
to	O
writing	O
a	O
full-fledged	O
Firefox	B-Operating_System
extension	I-Operating_System
,	O
user	O
scripting	O
is	O
a	O
very	O
modest	O
step	O
up	O
in	O
complexity	O
from	O
basic	O
web	O
programming	O
.	O
</s>
<s>
However	O
,	O
Greasemonkey	B-Operating_System
scripts	B-Language
are	O
limited	O
due	O
to	O
security	O
restrictions	O
imposed	O
by	O
Mozilla	O
's	O
XPCNativeWrappers	O
For	O
example	O
,	O
Greasemonkey	B-Operating_System
scripts	B-Language
do	O
not	O
have	O
access	O
to	O
many	O
of	O
Firefox	B-Application
's	O
components	O
,	O
such	O
as	O
the	O
download	O
manager	O
,	O
I/O	B-General_Concept
processes	I-General_Concept
or	O
its	O
main	O
toolbars	O
.	O
</s>
<s>
Additionally	O
,	O
Greasemonkey	B-Operating_System
scripts	B-Language
run	O
per	O
instance	O
of	O
a	O
matching	O
webpage	O
.	O
</s>
<s>
However	O
,	O
script	O
writers	O
have	O
been	O
using	O
cookies	O
and	O
Greasemonkey	B-Operating_System
even	O
offers	O
APIs	B-Application
such	O
as	O
GM_getValue	O
and	O
GM_setValue	O
to	O
overcome	O
this	O
.	O
</s>
<s>
File	O
hosting	O
servers	O
for	O
Greasemonkey	B-Operating_System
require	O
that	O
the	O
URLs	O
for	O
the	O
scripts	B-Language
end	O
with	O
.user.js	O
and	O
not	O
with	O
a	O
MIME	B-Application
type	I-Application
like	O
text/html	O
.	O
</s>
<s>
Support	O
for	O
HTTPS	B-Protocol
will	O
meet	O
with	O
Greasemonkey	B-Operating_System
's	O
built	O
in	O
update	O
checker	O
.	O
</s>
<s>
As	O
of	O
July	O
2019	O
,	O
the	O
Greasemonkey	B-Operating_System
project	O
lists	O
three	O
recommended	O
user	O
script	O
hostings	O
:	O
</s>
<s>
Gist	O
,	O
a	O
pastebin	O
service	O
operated	O
by	O
GitHub	B-Application
where	O
simple	O
files	O
are	O
hosted	O
.	O
</s>
<s>
HTTPS	B-Protocol
is	O
used	O
by	O
default	O
.	O
</s>
<s>
Greasy	O
Fork	B-Application
,	O
a	O
site	O
created	O
by	O
the	O
maintainer	O
of	O
userstyles.org	O
.	O
</s>
<s>
OpenUserJS.org,	O
a	O
site	O
that	O
started	O
as	O
a	O
fork	B-Application
for	O
the	O
deprecated	O
script	O
repository	O
userscripts.org	O
.	O
</s>
<s>
Greasemonkey	B-Operating_System
is	O
available	O
for	O
Firefox	B-Application
,	O
Flock	B-Protocol
and	O
GNOME	B-Language
Web	I-Language
(	O
formerly	O
called	O
Epiphany	B-Language
)	O
.	O
</s>
<s>
The	O
Greasemonkey	B-Operating_System
extension	B-Operating_System
for	O
Web	O
is	O
part	O
of	O
the	O
Web	B-Operating_System
extensions	I-Operating_System
package	O
.	O
</s>
<s>
However	O
,	O
this	O
extension	B-Operating_System
is	O
not	O
fully	O
compatible	O
as	O
of	O
release	O
2.15.1	O
,	O
since	O
some	O
Greasemonkey	B-Operating_System
API	B-Application
functions	I-Application
(	O
e.g.	O
</s>
<s>
There	O
are	O
also	O
custom	O
versions	O
for	O
SeaMonkey	B-Language
,	O
Songbird	B-Application
,	O
Pale	B-Protocol
Moon	I-Protocol
,	O
qutebrowser	B-Application
and	O
Falkon	B-Protocol
browser	O
.	O
</s>
