OpenAPI client code generator
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kilianmh 2623c6f45e Feature: update json-class
Json-class is now less opinionated.
It interns upcased symbols without param-casing them and does not
generate accessor functions any more.
Instead reader functions have been created for used slot functions.
2023-08-23 21:47:43 +02:00
code Feature: update json-class 2023-08-23 21:47:43 +02:00
test first commit 2023-02-24 20:47:01 +01:00
.gitignore Gitignore: add files that begin with # (hash) 2023-03-30 17:23:28 +02:00
COPYING first commit 2023-02-24 20:47:01 +01:00 Docs: add parse documentation 2023-06-13 12:05:55 +02:00
openapi-generator.asd Feat: json parameter as function arguments 2023-06-07 01:18:04 +02:00
version.sexp Version: bump to v0.0.2 2023-03-28 00:59:50 +02:00

Common Lisp OpenAPI Generator (openapi-generator)

OpenAPI-generator is an api client system generator.


  • Generation of OpenAPI ASDF/Quicklisp-loadable projects within one command
  • Support for path, (arbitrary) query, (arbitrary) header, (json) content parameters
  • Each system has dynamic variables for changing default server, query, headers, authentication, cookie, parse
  • Multiple function alias options (operation-id, path, summary, description)
  • Supported file formats / inputs: JSON, YAML, URL, local file, project-id on
  • Conversion of an OpenAPI spec into CLOS object -> explore API within inspector
  • Conversion of OpenAPI-2.0 or YAML files to OpenAPI-3.0 JSON with swagger converter (network connection required)


The main repository of this library is hosted on Codeberg. If you are viewing this anywhere else, it is just a mirror. Please use the Codeberg repository for collaboration (issues, pull requests, discussions, …). Thank you!


  • This software is still ALPHA quality. The APIs will be likely to change.
  • Make sure to review the openapi specification file if it is from an untrusted source or environment file before using openapi-generator, especially before using the generated system. This is to mitigate potential security risks such as code injection. For security vulnerabilities, please contact the maintainer of the library.


Load openapi-generator from Ultralisp via ql:quickload, or from local project folder via asdf:load-system

  (ql:quickload :openapi-generator)

Then put this in the REPL:

   :url ""
   :server ""
   :parse t)

This creates a client system to access the codeberg api in the projects folder within openapi-generator library and loads it (by default). Now you can use e.g.:

  (codeberg:repo-get "kilianmh" "openapi-generator")



  parse-openapi (name &key url collection-id source-directory content (dereference *dereference*))

Parse an OpenAPI to a openapi class object. This might be useful for exploration of the API specification, or you can pass it to the make-openapi-client function.

  (openapi-generator:parse-openapi "codeberg" :url "")

name of the openapi-file which is opened/created


url to a openapi specification file


apis-guru-id from


source-directory (name will be inserted from name parameter)


openapi spec file string


If set to true, pointers within openapi spec are dereferenced before parsing into openapi CLOS object. This improves discoverability for humans (and algorithms). Can be turned off for faster parsing.


    make-openapi-client (system-name
                         (server *server*) (parse *parse*) (query *query*) (headers *headers*)
                         (authorization *authorization*) (cookie *cookie*)
                         (alias (list :operation-id)) (system-directory :temporary) (load-system t)
                         openapi (api-name system-name) url source-directory collection-id
                         content (dereference *dereference*))
input same as parse-openapi



Name of file in openapi-generator/data folder



  • pathname-object -> pathname pathname-object + system-name


  • :temporary -> default, (uiop:temporary-directory)
  • :library -> openapi-generator/projects

default: nil, alternative: t, :json.

   :url ""
   :parse t)
  (wikitionary-api:find-word "oligopoly")

set default server variable in system (e.g. if server not/incorrect in spec file)


set default query parameters


set default headers (e.g. for api-tokens that have to be supplied often)


set default authorization value


set default cookie value


system exported functions: (multiple options possible):

  • :operation-id (param-cased operation-id) (default if there is are operation-id specified)
  • :summary (param-cased summary)
  • :description (param-case description)
  • :path (operation-type + path) (default if no operation-id specified)

Load system after making it (default: t)


If set to true (default), then the openapi spec is fully dereferenced before parsing into the CLOS object. This might be necessary to properly generate the system, e.g. if pointers are used for schemas. Can be turned off for faster system generation.


The request body content can be supplied either as "raw" Json or as lisp data structures. Both are type-checked at run-time. Look at JZON documentation for the type mapping You can supply the body-request to generated functions with the content keyword (default) or alternatively if existing in there is a title in the spec to the param-cased title keyword request-body id. Additionally for objects, the first level properties exist as function parameters.

   :url "")
  ;; make-openapi-client stacks as described in quickstart
   "SP187Y7NRSG3T9Z9WTSWNEN3XRV1YSJWS81C7JKV7" "imaginary-friends-zebras" "get-token-uri"
      \"sender\": \"STM9EQRAB3QAKF8NKTP15WJT7VHH4EWG3DJB4W29\",
  ;; make-openapi-client stacks as described in quickstart
   "SP187Y7NRSG3T9Z9WTSWNEN3XRV1YSJWS81C7JKV7" "imaginary-friends-zebras" "get-token-uri"
   :read-only-function-args ;; request-body title (only if existing in spec)
    "arguments" (list "0x0100000000000000000000000000000095"))
   :parse t)
  ;; first level of the request-body objects can be supplied as lisp datastructures
   "SP187Y7NRSG3T9Z9WTSWNEN3XRV1YSJWS81C7JKV7" "imaginary-friends-zebras" "get-token-uri"
   :arguments (list "0x0100000000000000000000000000000095"))
  ;; first level of the request-body objects can be supplied as JSON strings
   "SP187Y7NRSG3T9Z9WTSWNEN3XRV1YSJWS81C7JKV7" "imaginary-friends-zebras" "get-token-uri"
   :arguments "[\"0x0100000000000000000000000000000095\"]")
  ;; This example only works if you generate a valid apikey and insert it after Bearer
  ;; in the headers list
   :url ""
   :headers (list (cons "authorization" "Bearer <YOUR-API-KEY>"))
   :system-directory :temporary)

You have to first open an account and generate an api-key for using this api. If you supply value of authorization during client-creation, it will be saved directly in the file as variable. Beware and dont use this if in an untrusted environment.

  ;; only working with valid API-KEY
  (openai:retrieve-engine "davinci")

You can also add add :authorization "Bearer <YOUR-API-KEY>" to each function call. This is equivalent to adding it to the headers.

  :authorization "Bearer <YOUR-API-KEY>" ;; -> if not supplied during system generation
   :collection-id ""
   :parse nil)

This creates the api client for opendatasoft by accessing forthe URL. Here an example query:

  (opendatasoft:get-dataset "geonames-all-cities-with-a-population-1000")
from openapi data folder

Each time you load an api, a loadable json is stored in the openapi-generator/data folder. ELse you can put a file in the this folder manually.

  ;; file with that name has to be present in the folder openapi-generator/data
  (openapi-generator:make-openapi-client "codeberg")


  convert-to-openapi-3 (&key url content pathname (content-type "json"))

Conversion from Openapi 2.0 YAML/JSON to OpenAPI 3.0 JSON.

  (openapi-generator:convert-to-openapi-3 :url "")


Global variable that determines whether openapi spec is dereferenced before parsing into a CLOS object. Set to true by default. Can be overwritten in each call to parse-openapi / make-openapi-client.

Possible Future Improvements

  • modularize the project (e.g. separate systems for parsing, function generation, system generation)
  • extensibility with custom classes
  • Auto-generation of request body classes for parsing them into CLOS objects
  • Response validation & access functions for response content
  • websocket support
  • integrate JSON-Schema to create an expanded API-Object
  • generate client from command line interface (CLI)
  • integration in workflows (CI/CD, etc.)
  • more regression tests
  • support multiple implementations
  • offline openapi-spec conversion
  • integrate other api standards: json:api, raml, postman collection, har, OData, GraphQL, gRPC

License on generated code

Generated code is intentionally not subject to this project license. Code generated shall be considered AS IS and owned by the user. There are no warrantiesexpressed or impliedfor generated code. You can do what you wish with it, and once generated, the code is your responsibility and subject to the licensing terms that you deem appropriate.

Call for collaboration

Feel free to contribute by opening issues, pull request, feature requests etc. Your help is much appreciated.


(C) 2023 Kilian M. Haemmerle (


Licensed under the AGPLv3+ License.