Swagger2OpenAPI Converter

mermade · Developer Tools

Developer Tools No Auth Free & Open developer_tools

Converter and validator for Swagger 2.0 to OpenAPI 3.0.x definitions

Authentication

No authentication requiredFree to use with no key needed.

Sample Requests

GET Return a redirect to a badge svg file depending on a source definition's validity

Return a redirect to a badge svg file depending on a source definition's validity

https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/badge?url=https://example.com

Hover any highlighted part to learn what it does

curl -X GET "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/badge?url=https%3A%2F%2Fexample.com"

import requests
params = {
    "url": "https://example.com"
}
response = requests.get(
    "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/badge",
    params=params,
)
print(response.json())

const url = new URL('https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/badge');
url.searchParams.set('url', 'https://example.com');

const response = await fetch(url); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
)

func main() {
	baseURL, _ := url.Parse("https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/badge")
	q := baseURL.Query()
	q.Set("url", "https://example.com")
	baseURL.RawQuery = q.Encode()
	targetURL := baseURL.String()
	req, _ := http.NewRequest("GET", targetURL, nil)

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/badge")
uri.query = URI.encode_www_form({
  "url" => "https://example.com"
})

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Get.new(uri)

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/badge?" . http_build_query([
    "url" => "https://example.com"
]);
$opts = ["http" => [
    "method" => "GET",
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

GET Convert a Swagger 2.0 definition to OpenAPI 3.0.x from a URL

Convert a Swagger 2.0 definition to OpenAPI 3.0.x from a URL

https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/convert?url=https://example.com

Hover any highlighted part to learn what it does

curl -X GET "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/convert?url=https%3A%2F%2Fexample.com"

import requests
params = {
    "url": "https://example.com"
}
response = requests.get(
    "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/convert",
    params=params,
)
print(response.json())

const url = new URL('https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/convert');
url.searchParams.set('url', 'https://example.com');

const response = await fetch(url); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
)

func main() {
	baseURL, _ := url.Parse("https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/convert")
	q := baseURL.Query()
	q.Set("url", "https://example.com")
	baseURL.RawQuery = q.Encode()
	targetURL := baseURL.String()
	req, _ := http.NewRequest("GET", targetURL, nil)

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/convert")
uri.query = URI.encode_www_form({
  "url" => "https://example.com"
})

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Get.new(uri)

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/convert?" . http_build_query([
    "url" => "https://example.com"
]);
$opts = ["http" => [
    "method" => "GET",
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

GET Validate an OpenAPI 3.0.x definition

Validate an OpenAPI 3.0.x definition

https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/validate?url=https://example.com

Hover any highlighted part to learn what it does

curl -X GET "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/validate?url=https%3A%2F%2Fexample.com"

import requests
params = {
    "url": "https://example.com"
}
response = requests.get(
    "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/validate",
    params=params,
)
print(response.json())

const url = new URL('https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/validate');
url.searchParams.set('url', 'https://example.com');

const response = await fetch(url); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
)

func main() {
	baseURL, _ := url.Parse("https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/validate")
	q := baseURL.Query()
	q.Set("url", "https://example.com")
	baseURL.RawQuery = q.Encode()
	targetURL := baseURL.String()
	req, _ := http.NewRequest("GET", targetURL, nil)

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/validate")
uri.query = URI.encode_www_form({
  "url" => "https://example.com"
})

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Get.new(uri)

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://api.apis.guru/v2/specs/mermade.org.uk/openapi-converter/1.0.0/validate?" . http_build_query([
    "url" => "https://example.com"
]);
$opts = ["http" => [
    "method" => "GET",
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

Postman Setup Guide

Get Postman ↗

See official documentation for authentication and setup.

What can you build with Swagger2OpenAPI Converter?

Swagger2OpenAPI Converter is a Developer Tools API. Developers commonly use developer tools APIs for:

automating code review and quality checks
integrating CI/CD pipelines and build systems
managing feature flags and A/B tests
monitoring errors and application performance
generating and validating test data

No authentication required. This API is open — no signup or key needed. Ideal for quick prototypes and public-facing features. Swagger2OpenAPI Converter is free to use, making it a low-risk choice to experiment with.

New to APIs? Read our beginner's guide

Open documentation ↗