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description=OpenAPI is a standard for documenting REST APIs;

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Text of the page (random words):
what is an openapi specification fern documentation for ai agents a documentation index is available at the root level at llms txt append llms txt to any url for a page level index or md for the markdown version of any page search ask ai book a demo log in start for free overview what is an api definition project structure openapi overview overlays overrides authentication servers sync your specification endpoints extensions integrate your server framework generators yml reference asyncapi openrpc grpc fern definition what is an api definition project structure overview overlays overrides authentication servers sync your specification http json endpoints webhooks multipart form uploads server sent events overview api version audiences availability base path default values enum descriptions names and availability request response examples api explorer control global headers ignoring elements sdk method names sdk variables tag display names parameter names property names idempotency pagination retry behavior schema names server names and url templating fastapi generators yml reference overview overrides authentication servers sync your specification publish subscribe operations message formats message bindings overview audiences availability request response examples ignoring elements server names overview overrides authentication servers sync your specification json rpc methods overview audiences availability request response examples ignoring elements sdk method names sdk group names server names overview overrides authentication servers sync your specification grpc services streaming error handling generators yml reference overview authentication types overview http json endpoints multipart form uploads bytes server sent events webhooks websockets errors imports examples audiences availability overview environments global headers errors packages depending on other apis export to openapi book a demo log in start for free english light on this page best practices set up your fern folder scroll to top openapi what is an openapi specification ask a question copy page view as markdown more actions the openapi specification oas is a framework used by developers to document rest apis the specification is written in json or yaml and contains all of your endpoints parameters schemas and authentication schemes fern is compatible with the latest oas release which is currently v3 1 1 below is an example of an openapi file openapi yml 1 openapi 3 0 2 2 info 3 title petstore openapi 3 0 4 description 5 this is a sample pet store server based on the openapi 3 0 specification 6 paths 7 pet 8 put 9 tags 10 pet 11 summary update an existing pet 12 description update an existing pet by id 13 operationid updatepet 14 requestbody 15 description update an existent pet in the store 16 content 17 application json 18 schema 19 ref components schemas pet 20 required true 21 responses 22 200 23 description successful operation 24 content 25 application json 26 schema 27 ref components schemas pet 28 400 29 description invalid id supplied 30 404 31 description pet not found 32 405 33 description validation exception 34 security 35 api_key 36 components 37 schemas 38 category 39 type object 40 properties 41 id 42 type integer 43 format int64 44 example 1 45 name 46 type string 47 example dogs 48 tag 49 type object 50 properties 51 id 52 type integer 53 format int64 54 name 55 type string 56 pet 57 required 58 name 59 photourls 60 type object 61 properties 62 id 63 type integer 64 format int64 65 example 10 66 name 67 type string 68 example doggie 69 category 70 ref components schemas category 71 photourls 72 type array 73 items 74 type string 75 tags 76 type array 77 items 78 ref components schemas tag 79 status 80 type string 81 description pet status in the store 82 enum 83 available 84 pending 85 sold 86 securityschemes 87 api_key 88 type apikey 89 name api_key 90 in header best practices follow these best practices to ensure your openapi specification generates high quality sdks and documentation organize with proper project structure follow the instructions at project structure to clearly organize the directories that contain your definition and other related files add operationid to endpoints include a clear operationid for each endpoint to control the function names generated in your sdks or use extensions to customize group and method names reference schemas instead of inlining define reusable schemas in the components schemas section and reference them with ref this promotes consistency reduces duplication and makes maintenance easier example of referencing schemas openapi yml 1 paths 2 pets 3 post 4 requestbody 5 content 6 application json 7 schema 8 ref components schemas pet clean reference 9 responses 10 200 11 content 12 application json 13 schema 14 ref components schemas pet reused easily 15 components 16 schemas 17 pet defined once used everywhere 18 type object 19 properties 20 name 21 type string 22 status 23 type string 24 enum available pending sold use overlays and fern extensions for customization customize your specification using fern extensions housed in an overlay file this lets you modify generation behavior without changing your core openapi definition once your openapi spec follows these practices you re ready to set up your fern folder set up your fern folder start by initializing your fern folder with an openapi spec file url 1 fern init openapi path to openapi this will initialize a directory like the following fern fern config json generators yml openapi openapi yml your spec was this page helpful yes no edit this page previous project structure next overlays checking status soc 2 soc 2 type ii 2026 fern birch solutions inc a postman company documentation sdks docs ask fern cli reference api definitions openapi asyncapi openrpc grpc resources blog support pricing company brand kit privacy policy terms of service api definitions api definitions import and configure your api specifications english api definitions api definitions import and configure your api specifications