Lift your API spec to OpenAPI 3

Drop in a Swagger 2.0 spec as JSON or YAML and get the OpenAPI 3 output Swagger's official converter produces, with its bugs fixed. Every step runs in your browser. Nothing leaves this browser.

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swagger.yaml2.0

swagger: "2.0"
host: api.example.com
basePath: /v1
schemes: [https]
consumes: [application/json]
definitions:
  Order:
    $ref: "#/definitions/NewOrder"

openapi.yaml3.0

openapi: 3.0.1
servers:
- url: https://api.example.com/v1
components:
  schemas:
    Order:
      $ref: "#/components/schemas/NewOrder"

Swagger 2.0

swagger.json

{
  "swagger": "2.0",
  "info": {
    "title": "Orders API",
    "description": "Create and track customer orders.",
    "version": "1.4.0"
  },
  "host": "api.example.com",
  "basePath": "/v1",
  "schemes": [
    "https"
  ],
  "consumes": [
    "application/json"
  ],
  "produces": [
    "application/json"
  ],
  "paths": {
    "/orders": {
      "get": {
        "summary": "List orders",
        "operationId": "listOrders",
        "parameters": [
          {
            "name": "limit",
            "in": "query",
            "type": "integer",
            "format": "int32",
            "default": 20
          }
        ],
        "responses": {
          "200": {
            "description": "A list of orders",
            "schema": {
              "type": "array",
              "items": {
                "$ref": "#/definitions/Order"
              }
            }
          }
        }
      },
      "post": {
        "summary": "Create an order",
        "operationId": "createOrder",
        "parameters": [
          {
            "name": "order",
            "in": "body",
            "required": true,
            "schema": {
              "$ref": "#/definitions/NewOrder"
            }
          }
        ],
        "responses": {
          "201": {
            "description": "Order created",
            "schema": {
              "$ref": "#/definitions/Order"
            }
          }
        }
      }
    }
  },
  "definitions": {
    "NewOrder": {
      "type": "object",
      "required": [
        "productId",
        "quantity"
      ],
      "properties": {
        "productId": {
          "type": "string"
        },
        "quantity": {
          "type": "integer",
          "minimum": 1
        }
      }
    },
    "Order": {
      "allOf": [
        {
          "$ref": "#/definitions/NewOrder"
        },
        {
          "type": "object",
          "properties": {
            "id": {
              "type": "string"
            },
            "status": {
              "type": "string",
              "enum": [
                "pending",
                "shipped"
              ]
            }
          }
        }
      ]
    }
  }
}

{
  "swagger": "2.0",
  "info": {
    "title": "Orders API",
    "description": "Create and track customer orders.",
    "version": "1.4.0"
  },
  "host": "api.example.com",
  "basePath": "/v1",
  "schemes": [
    "https"
  ],
  "consumes": [
    "application/json"
  ],
  "produces": [
    "application/json"
  ],
  "paths": {
    "/orders": {
      "get": {
        "summary": "List orders",
        "operationId": "listOrders",
        "parameters": [
          {
            "name": "limit",
            "in": "query",
            "type": "integer",
            "format": "int32",
            "default": 20
          }
        ],
        "responses": {
          "200": {
            "description": "A list of orders",
            "schema": {
              "type": "array",
              "items": {
                "$ref": "#/definitions/Order"
              }
            }
          }
        }
      },
      "post": {
        "summary": "Create an order",
        "operationId": "createOrder",
        "parameters": [
          {
            "name": "order",
            "in": "body",
            "required": true,
            "schema": {
              "$ref": "#/definitions/NewOrder"
            }
          }
        ],
        "responses": {
          "201": {
            "description": "Order created",
            "schema": {
              "$ref": "#/definitions/Order"
            }
          }
        }
      }
    }
  },
  "definitions": {
    "NewOrder": {
      "type": "object",
      "required": [
        "productId",
        "quantity"
      ],
      "properties": {
        "productId": {
          "type": "string"
        },
        "quantity": {
          "type": "integer",
          "minimum": 1
        }
      }
    },
    "Order": {
      "allOf": [
        {
          "$ref": "#/definitions/NewOrder"
        },
        {
          "type": "object",
          "properties": {
            "id": {
              "type": "string"
            },
            "status": {
              "type": "string",
              "enum": [
                "pending",
                "shipped"
              ]
            }
          }
        }
      ]
    }
  }
}

Swagger 2.0 · JSON109 lines · 2.1 KB

OpenAPI 3.0 · bugs fixed

openapi.json

{
  "openapi": "3.0.1",
  "info": {
    "title": "Orders API",
    "description": "Create and track customer orders.",
    "version": "1.4.0"
  },
  "servers": [
    {
      "url": "https://api.example.com/v1"
    }
  ],
  "paths": {
    "/orders": {
      "get": {
        "summary": "List orders",
        "operationId": "listOrders",
        "parameters": [
          {
            "name": "limit",
            "in": "query",
            "schema": {
              "type": "integer",
              "format": "int32",
              "default": 20
            }
          }
        ],
        "responses": {
          "200": {
            "description": "A list of orders",
            "content": {
              "application/json": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Order"
                  }
                }
              }
            }
          }
        }
      },
      "post": {
        "summary": "Create an order",
        "operationId": "createOrder",
        "requestBody": {
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/NewOrder"
              }
            }
          },
          "required": true
        },
        "responses": {
          "201": {
            "description": "Order created",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Order"
                }
              }
            }
          }
        },
        "x-codegen-request-body-name": "order"
      }
    }
  },
  "components": {
    "schemas": {
      "NewOrder": {
        "required": [
          "productId",
          "quantity"
        ],
        "type": "object",
        "properties": {
          "productId": {
            "type": "string"
          },
          "quantity": {
            "minimum": 1,
            "type": "integer"
          }
        }
      },
      "Order": {
        "allOf": [
          {
            "$ref": "#/components/schemas/NewOrder"
          },
          {
            "type": "object",
            "properties": {
              "id": {
                "type": "string"
              },
              "status": {
                "type": "string",
                "enum": [
                  "pending",
                  "shipped"
                ]
              }
            }
          }
        ]
      }
    }
  },
  "x-original-swagger-version": "2.0"
}

1 paths2 operations2 schemas0 security

Up to date

Sample converted. Paste your own Swagger 2.0 spec to begin.

Live convertFix Swagger bugs

What changes

Every Swagger 2.0 concept, remapped.

SpecLift follows the same rules as Swagger's converter, so tooling that expects its output keeps working.

host + basePath + schemesservers[].url
definitionscomponents.schemas
in: bodyrequestBody.content
in: formDatarequestBody (form / multipart)
consumes / producescontent media types
type: filetype: string, format: binary
collectionFormatstyle + explode
securityDefinitionscomponents.securitySchemes
type: basictype: http, scheme: basic
flow: accessCodeflows.authorizationCode
parameters / responsescomponents.*
#/definitions/…#/components/schemas/…

Swagger's bugs, fixed

Same rules. Fewer surprises.

In a few places Swagger's converter writes invalid OpenAPI or quietly drops data. SpecLift fixes these by default. Turn off “Fix Swagger bugs” for byte-for-byte Swagger output.

Swaggertype: file inside schemas stays fileSpecLifttype: string, format: binary
Swaggerdate defaults become "…T00:00:00.000+00:00"SpecLiftdates stay "2021-01-01"
Swaggerarray defaults become text "[\"a\"]"SpecLiftreal arrays ["a"]
Swaggernumeric form enums become ["1", "5"]SpecLiftnumbers stay numbers
Swaggerobject examples become Java text "{a=1}"SpecLiftexamples stay JSON
Swaggershared params lose example / nullable after first useSpecLiftevery use keeps them
Swaggerdefaults, enums, readOnly, discriminators silently droppedSpecLiftkept in the output
Swaggeroperation schemes and x- extensions droppedSpecLiftoperation servers and extensions kept

Private by design

Your API never leaves the tab.

Internal specs often describe systems nobody outside your team should see. SpecLift has no backend to send them to.

Runs in your browser

Files are read with the FileReader API, converted in memory and downloaded from a local Blob.

No tracking, no storage

No accounts, analytics, telemetry or third-party fonts. Close the tab and nothing remains.

Swagger-exact on demand

With bug fixes off, output is identical to converter.swagger.io, key order included. That is tested on 99 real-world APIs and 54 edge-case fixtures.