Sign Up for Free

RunKit +

Try any Node.js package right in your browser

This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 400,000 packages pre-installed, including swagger2openapi with all npm packages installed. Try it out:

var swagger2openapi = require("swagger2openapi")

This service is provided by RunKit and is not affiliated with npm, Inc or the package authors.

swagger2openapi v5.3.1

Convert Swagger 2.0 definitions to OpenApi 3.0 and validate



OpenAPI Validation Build Tested on Tested on Mermade OpenAPIs Coverage Status Known Vulnerabilities Greenkeeper badge

Convert Swagger 2.0 definitions into OpenApi 3.0.x

The online version of the converter/validator runs on a Linode VPS. If you are considering a hosted server, please sign up through this link so we both receive free credit.

Currently tracking v3.0.x


This is a node.js module, which you can run on the command line. First ensure you have npm installed (tested on version 6.1+), and then install as follows:

npm install -g swagger2openapi

Or, add it to your node.js projects as shown below in option B.


A. Command line:

swagger2openapi [options] [filename|url]
  --refSiblings        mode to handle $ref's with sibling properties
                                        [choices: "remove", "preserve", "allOf"]
  --resolveInternal    resolve internal references also                [boolean]
  --warnProperty       Property name to use for warning extensions
                                             [string] [default: "x-s2o-warning"]
  --version            Show version number                             [boolean]
  -c, --components     output information to unresolve a definition    [boolean]
  -d, --debug          enable debug mode, adds specification-extensions[boolean]
  -e, --encoding       encoding for input/output files[string] [default: "utf8"]
  -f, --fatal          make resolution errors fatal                    [boolean]
  -h, --help           Show help                                       [boolean]
  -i, --indent         JSON indent to use, defaults to 4 spaces         [string]
  -o, --outfile        the output file to write to                      [string]
  -p, --patch          fix up small errors in the source definition    [boolean]
  -r, --resolve        resolve external references                     [boolean]
  -t, --targetVersion  override default target version of 3.0.0         [string]
  -u, --url            url of original spec, creates x-origin entry     [string]
  -v, --verbose        increase verbosity                                [count]
  -w, --warnOnly       Do not throw on non-patchable errors, add warning
                       extensions                                      [boolean]
  -y, --yaml           write YAML, default JSON (overridden by --outfile
                       filepath extension)                             [boolean]
  -b, --rbname         Extension to use to preserve body parameter names in
                       converted operations ("" == disabled)
                                                          [string] [default: ""]

B. Node.js API:

const converter = require('swagger2openapi');
let options = {};
//options.patch = true; // fix up small errors in the source definition
//options.warnOnly = true; // Do not throw on non-patchable errors
converter.convertObj(swagger, options, function(err, options){
  // options.openapi contains the converted definition
// also available are asynchronous convertFile, convertUrl, convertStr and convertStream functions
// if you omit the callback parameter, you will instead receive a Promise

Note that the options object passed in is modified/extended by the convert* functions.

See the boast command-line tool for a fuller CLI tool for converting, validating and linting.

See here for complete documentation of the options object.

C. Browser:

Or use the online version which also includes its own API.

Browser Support

See initial documentation.


OpenAPI 3.0.x validation

oas-validate can be used as a validator if given one or more existing OpenAPI 3.x definitions. The validator (however it is called) uses WHATWG URL parsing if available (node 7.x and above). The validator can have a linting mode enabled with the --lint option. Rules are defined here. Contributions of rules and rule actions for the linter are very much appreciated.

oas-validate.js [options] {path-to-docs}...

  --lint            lint the definition                                [boolean]
  --validateSchema  Run schema validation step: first, last* or never   [string]
  --warnOnly        Do not throw on non-patchable errors               [boolean]
  -h, --help        Show help                                          [boolean]
  --version         Show version number                                [boolean]
  -e, --encoding    encoding for input/output files   [string] [default: "utf8"]
  -f, --fail        path to docs expected to fail                       [string]
  -j, --jsonschema  path to alternative JSON schema                     [string]
  -l, --laxurls     lax checking of empty urls                         [boolean]
  -m, --mediatype   check media-types against RFC pattern              [boolean]
  -n, --nopatch     do not patch minor errors in the source definition [boolean]
  -o, --output      output conversion result  [string] [default: "openapi.yaml"]
  -q, --quiet       do not show test passes on console, for CI         [boolean]
  -r, --resolve     resolve external references                        [boolean]
  -s, --stop        stop on first error                                [boolean]
  -v, --verbose     increase verbosity                                   [count]
  -w, --whatwg      enable WHATWG URL parsing                          [boolean]
  -y, --yaml        skip YAML-safe test                                [boolean]

Reference preservation

swagger2openapi by default preserves almost all $ref JSON references in your API definition, and does not dereference every item, as with some model-based parsers. The exception is internal references within externally referenced documents. To enable internal $ref resolution across the whole document, use the --resolveInternal option, which also disables creation of $refs for shared requestBodies.

Schema transformations

swagger2openapi will automatically 'repair' a number of problems where non-compliant Swagger 2.0 schemas have been used. It will attempt to transform JSON schemas (used incorrectly) into OpenAPI 3.0.x Schema objects.

Specification extensions

swagger2openapi has support for a limited number of real-world specification extensions which have a direct bearing on the conversion. All other specification extensions are left untouched. swagger2openapi is swaggerplusplus-compatible.

It is expected to be able to configure the process of specification-extension modification using options or a plugin mechanism in a future release.


To run a test-suite:

node oas-validate [-f {path-to-expected-failures}]... [{path-to-APIs|single-file...}]

The test harness currently expects files with a .json or .yaml extension, or a single named file, and has been tested on Node.js versions 8.x and 10.x LTS (it is not recommended to run the test suite under Node.js versions >=7.0.0 and <8.7.0 because of this bug) against

Additionally swagger2openapi has been tested on a corpus of 74,426 real-world valid Swagger 2.0 definitions from GitHub and SwaggerHub. However, if you have a definition which causes errors in the converter or does not pass validation, please do not hesitate to raise an issue.

Regression tests

Regression tests (thanks @domharrington) live in the /test directory and can be run with npx mocha. Each sub-directory of s2o-test should contain an input swagger.yaml file, an expected output openapi.yaml file and an optional options.yaml file. You can put private test cases in sub-directories starting with an underscore character. In the resolver sub-directory, each directory should contain an input.yaml, an output.yaml and an optional options.yaml file.

Version history


BSD-3-Clause except the openapi-3.0.json schema, which is taken from the OpenAPI-Specification which is licensed under the Apache-2 license.


RunKit is a free, in-browser JavaScript dev environment for prototyping Node.js code, with every npm package installed. Sign up to share your code.
Sign Up for Free