<s>
The	O
OpenAPI	B-Architecture
Specification	I-Architecture
,	O
previously	O
known	O
as	O
the	O
Swagger	B-Application
Specification	O
,	O
is	O
a	O
specification	O
for	O
a	O
machine-readable	B-General_Concept
interface	B-General_Concept
definition	I-General_Concept
language	I-General_Concept
for	O
describing	O
,	O
producing	O
,	O
consuming	O
and	O
visualizing	O
web	B-General_Concept
services	I-General_Concept
.	O
</s>
<s>
Previously	O
part	O
of	O
the	O
Swagger	B-Application
framework	O
,	O
it	O
became	O
a	O
separate	O
project	O
in	O
2016	O
,	O
overseen	O
by	O
the	O
OpenAPI	B-Architecture
Initiative	I-Architecture
,	O
an	O
open-source	O
collaboration	O
project	O
of	O
the	B-Operating_System
Linux	I-Operating_System
Foundation	I-Operating_System
.	O
</s>
<s>
Swagger	B-Application
and	O
some	O
other	O
tools	O
can	O
generate	O
code	O
,	O
documentation	O
and	O
test	O
cases	O
from	O
interface	O
files	O
.	O
</s>
<s>
Swagger	B-Application
development	O
began	O
in	O
early	O
2010	O
by	O
Tony	O
Tam	O
,	O
who	O
was	O
working	O
at	O
online	O
dictionary	O
company	O
Wordnik	O
.	O
</s>
<s>
In	O
March	O
2015	O
,	O
SmartBear	B-General_Concept
Software	I-General_Concept
acquired	O
the	O
open-source	O
Swagger	B-Application
API	B-General_Concept
specification	O
from	O
Reverb	O
Technologies	O
,	O
Wordnik	O
's	O
parent	O
company	O
.	O
</s>
<s>
In	O
November	O
2015	O
,	O
SmartBear	B-General_Concept
announced	O
that	O
it	O
was	O
creating	O
a	O
new	O
organization	O
called	O
the	O
OpenAPI	B-Architecture
Initiative	I-Architecture
under	O
the	O
sponsorship	O
of	O
the	B-Operating_System
Linux	I-Operating_System
Foundation	I-Operating_System
.	O
</s>
<s>
Other	O
founding	O
member	O
companies	O
included	O
3scale	O
,	O
Apigee	B-General_Concept
,	O
Capital	O
One	O
,	O
Google	B-Application
,	O
IBM	O
,	O
Intuit	O
,	O
Microsoft	O
,	O
PayPal	O
,	O
and	O
Restlet	O
.	O
</s>
<s>
SmartBear	B-General_Concept
donated	O
the	O
Swagger	B-Application
specification	O
to	O
the	O
new	O
group	O
.	O
</s>
<s>
RAML	B-Application
and	O
were	O
also	O
under	O
consideration	O
by	O
the	O
group	O
.	O
</s>
<s>
On	O
1	O
January	O
2016	O
,	O
the	O
Swagger	B-Application
specification	O
was	O
renamed	O
the	O
OpenAPI	B-Architecture
Specification	I-Architecture
(	O
OAS	O
)	O
and	O
was	O
moved	O
to	O
a	O
new	O
GitHub	B-Application
repository	B-Application
.	O
</s>
<s>
In	O
September	O
2016	O
,	O
the	O
API	B-General_Concept
World	O
conference	O
presented	O
an	O
API	B-General_Concept
Infrastructure	O
award	O
to	O
SmartBear	B-General_Concept
for	O
its	O
ongoing	O
work	O
on	O
Swagger	B-Application
.	O
</s>
<s>
In	O
July	O
2017	O
,	O
the	O
OpenAPI	B-Architecture
Initiative	I-Architecture
released	O
version	O
3.0.0	O
of	O
its	O
specification	O
.	O
</s>
<s>
MuleSoft	B-General_Concept
,	O
the	O
main	O
contributor	O
to	O
the	O
alternative	O
RESTful	B-Application
API	I-Application
Modeling	I-Application
Language	I-Application
(	O
RAML	B-Application
)	O
,	O
joined	O
the	O
OAS	O
and	O
open-sourced	O
its	O
API	B-General_Concept
Modeling	O
Framework	O
tool	O
,	O
which	O
can	O
generate	O
OAS	O
documents	O
from	O
RAML	B-Application
input	O
.	O
</s>
<s>
In	O
February	O
2021	O
,	O
the	O
OpenAPI	B-Architecture
Initiative	I-Architecture
released	O
version	O
3.1.0	O
.	O
</s>
<s>
Major	O
changes	O
in	O
OpenAPI	B-Architecture
Specification	I-Architecture
3.1.0	O
include	O
JSON	B-General_Concept
schema	O
vocabularies	O
alignment	O
,	O
new	O
top-level	O
elements	O
for	O
describing	O
webhooks	O
that	O
are	O
registered	O
and	O
managed	O
out	O
of	O
band	O
,	O
support	O
for	O
identifying	O
API	B-General_Concept
licenses	O
using	O
the	O
standard	O
SPDX	O
identifier	O
,	O
allowance	O
of	O
descriptions	O
alongside	O
the	O
use	O
of	O
schema	O
references	O
and	O
a	O
change	O
to	O
make	O
the	O
PathItems	O
object	O
optional	O
in	O
order	O
to	O
simplify	O
creation	O
of	O
reusable	O
libraries	O
of	O
components	O
.	O
</s>
<s>
The	O
paradigm	O
of	O
agreeing	O
on	O
an	O
API	B-General_Concept
contract	O
first	O
and	O
then	O
programming	O
business	O
logic	O
afterwards	O
,	O
in	O
contrast	O
to	O
coding	O
the	O
program	O
first	O
and	O
then	O
writing	O
a	O
retrospective	O
description	O
of	O
its	O
behavior	O
as	O
the	O
contract	O
,	O
is	O
called	O
contract-first	O
development	O
.	O
</s>
<s>
Since	O
the	O
interface	O
is	O
determined	O
before	O
any	O
code	O
is	O
written	O
,	O
downstream	O
developers	O
can	O
mock	O
the	O
server	B-Application
behavior	O
and	O
start	O
testing	O
right	O
away	O
.	O
</s>
<s>
The	O
OpenAPI	B-Architecture
Specification	I-Architecture
is	O
language-agnostic	O
.	O
</s>
<s>
With	O
OpenAPI	O
's	O
declarative	B-Language
resource	O
specification	O
,	O
clients	O
can	O
understand	O
and	O
consume	O
services	O
without	O
knowledge	O
of	O
server	B-Application
implementation	O
or	O
access	O
to	O
the	O
server	B-Application
code	O
.	O
</s>
<s>
The	O
OpenAPI	B-Architecture
Initiative	I-Architecture
maintains	O
a	O
list	O
of	O
implementations	O
for	O
version	O
3.0	O
of	O
the	O
specification	O
.	O
</s>
<s>
SmartBear	B-General_Concept
still	O
brands	O
its	O
OpenAPI	O
tools	O
with	O
the	O
Swagger	B-Application
moniker	O
.	O
</s>
<s>
The	O
Swagger	B-Application
UI	O
framework	O
allows	O
both	O
developers	O
and	O
non-developers	O
to	O
interact	O
with	O
the	O
API	B-General_Concept
in	O
a	O
sandbox	O
UI	O
that	O
gives	O
insight	O
into	O
how	O
the	O
API	B-General_Concept
responds	O
to	O
parameters	O
and	O
options	O
.	O
</s>
<s>
Swagger	B-Application
can	O
handle	O
both	O
JSON	B-General_Concept
and	O
XML	B-Protocol
.	O
</s>
<s>
Swagger	B-Application
Codegen	O
contains	O
a	O
template-driven	O
engine	O
to	O
generate	O
documentation	O
,	O
API	B-General_Concept
clients	O
and	O
server	B-Application
stubs	O
in	O
different	O
languages	O
by	O
parsing	O
the	O
OpenAPI	O
definition	O
.	O
</s>
<s>
In	O
July	O
,	O
2018	O
,	O
William	O
Cheng	O
,	O
the	O
top	O
contributor	O
to	O
Swagger	B-Application
Codegen	O
,	O
and	O
over	O
40	O
other	O
contributors	O
to	O
Swagger	B-Application
Codegen	O
forked	B-Application
the	O
code	O
into	O
a	O
project	O
named	O
under	O
the	O
OpenAPI	O
Tools	O
organization	O
.	O
</s>
<s>
The	O
OpenAPI	B-Architecture
Initiative	I-Architecture
sponsors	O
an	O
annual	O
API	B-General_Concept
Specifications	O
Conference	O
(	O
ASC	O
)	O
.	O
</s>
<s>
The	O
event	O
has	O
its	O
origins	O
in	O
the	O
API	B-General_Concept
Strategy	O
and	O
Practice	O
Conference	O
(	O
APIStrat	O
)	O
that	O
ran	O
for	O
many	O
years	O
and	O
became	O
part	O
of	O
the	O
OpenAPI	B-Architecture
Initiative	I-Architecture
in	O
2016	O
.	O
</s>
