Easy Steps to Convert Postman Collections to OpenAPI 3.0

Are you drowning in Postman collections but need OpenAPI 3.0 specifications for your project? You're not alone! Many developers find themselves stuck with valuable API documentation in Postman format when they really need the industry-standard OpenAPI format.

Don't worry - I've got you covered with this comprehensive conversion guide that will transform your workflow and save you countless hours of manual work!

The Hidden Power of OpenAPI Specifications

Before we dive into the conversion process, let's explore why making this switch is worth your time:

• Universal Language: OpenAPI has become the lingua franca of API documentation, making your APIs instantly understandable to developers worldwide
• Tool Ecosystem: Unlock access to hundreds of tools built around the OpenAPI ecosystem
• Future-Proof Documentation: Ensure your API documentation remains relevant as industry standards evolve
• Developer Experience: Create beautiful, interactive documentation that makes your API a joy to use

Now let's explore the various paths to conversion success!

Method 1: The NPM Package Solution - Quick and Programmatic

The postman-to-openapi npm package offers a developer-friendly approach to conversion. Here's how to leverage it:

Step 1: Install the Package

Fire up your terminal and run:

npm install postman-to-openapi 

For yarn enthusiasts:

yarn add postman-to-openapi 

Step 2: Create Your Conversion Script

With the package installed, you can now write a simple Node.js script:

const postmanToOpenApi = require('postman-to-openapi') const postmanCollection = './path/to/your/collection.json' const outputFile = './output/openapi.yml' async function convertCollection() { try { const result = await postmanToOpenApi(postmanCollection, outputFile, { defaultTag: 'General' }) console.log(`Success! OpenAPI specs available at: ${result}`) } catch (err) { console.error('Conversion failed:', err) } } convertCollection() 

Step 3: Customize Your Conversion

The real magic happens when you customize the conversion process:

const postmanToOpenApi = require('postman-to-openapi') const postmanCollection = './path/to/your/collection.json' const outputFile = './output/openapi.json' async function convertCollection() { try { const result = await postmanToOpenApi(postmanCollection, outputFile, { defaultTag: 'MyAPI', outputFormat: 'json', includeAuthInfoInExample: true }) console.log(`Success! OpenAPI specs available at: ${result}`) } catch (err) { console.error('Conversion failed:', err) } } convertCollection() 

This approach is perfect for developers who need to integrate conversion into their CI/CD pipelines or perform batch conversions.

Method 2: The No-Code Solution - Apidog to the Rescue

Not everyone wants to write code for conversion. If you prefer a visual approach, Apidog offers an elegant solution:

1. Sign in to your Apidog account
2. Navigate to "Settings" and find the "Import" option
3. Select your Postman collection file for import

Import Your Postman Collection to Apidog

1. After importing, click the "Export Data" button and select "OpenAPI 3.0 Format"

Export Your Postman Data to OpenAPI 3.0 Format

But here's what makes Apidog truly special - it's not just a converter but a complete Postman alternative with a generous free tier:

• Unlimited API Creation - no artificial limits on your creativity
• No Flow Restrictions - run unlimited collection tests
• Unlimited API Calls - test to your heart's content
• Unlimited Mock Server Calls - perfect for frontend development

All these features come with the Apidog Free Version! And if you need more, their $9/month plan offers everything in Postman's $39/month Professional Plan.

Method 3: Direct from the Source - Postman API

For those who prefer to go straight to the source, Postman's own API can handle the conversion:

1. Retrieve your Postman API key from account settings
2. Execute this curl command (replacing the placeholders):

curl --location --request GET 'https://api.getpostman.com/collections/{{collectionId}}/transformations' \ --header 'Content-Type: application/json' \ --header 'x-api-key: {{postman-api-key}}' 

1. Save the response to create your OpenAPI specification

Method 4: Quick Online Converters

Need a one-time conversion without any setup? Online tools have you covered:

1. Visit an online converter like p2o.defcon007.com
2. Upload your Postman collection or paste its URL
3. Click "Convert" and download your OpenAPI specification

This approach is perfect for occasional conversions or when you're away from your development environment.

Mastering the Conversion Process: Pro Tips

Even with great tools, conversion can sometimes be tricky. Here are some battle-tested strategies:

• Divide and Conquer: Split massive collections into logical chunks before conversion
• Folder Organization: Use Postman folders to create a clean tag structure in OpenAPI
• Example Enrichment: Add detailed examples in Postman to enhance your OpenAPI documentation
• Pre-Conversion Cleanup: Remove any inconsistencies or deprecated endpoints before conversion
• Post-Conversion Validation: Always validate your OpenAPI specification with a dedicated validator

The most successful conversions start with well-organized Postman collections that follow consistent naming and documentation practices.

Beyond Conversion: Making the Most of OpenAPI

Once you've successfully converted your Postman collections, you can:

• Generate client SDKs in multiple programming languages
• Create interactive API documentation with tools like Swagger UI or Redoc
• Implement contract testing to ensure API compliance
• Design new API endpoints using the OpenAPI-first approach

The OpenAPI ecosystem continues to grow, making your investment in conversion increasingly valuable over time.

Your Conversion Journey Starts Now

Converting from Postman to OpenAPI 3.0 doesn't have to be complicated. Whether you choose the programmatic approach with npm packages, the visual route with Apidog, or quick online converters, you now have all the tools needed for successful conversion.

What conversion challenges are you facing with your Postman collections? Share your experiences in the comments below, and let's help each other navigate the path to OpenAPI excellence!

Frequently Asked Questions

Q: Will I lose any information when converting from Postman to OpenAPI?
A: Most converters preserve the core information, but some Postman-specific features might not have direct equivalents in OpenAPI.

Q: Can I convert collections with environment variables?
A: Yes, but you'll need to ensure your converter supports environment variable handling or make adjustments post-conversion.

Q: How do I handle authentication information during conversion?
A: Most converters offer options to include or exclude authentication details. For sensitive information, consider excluding it and adding it manually later.

Q: What's the best approach for very large collections?
A: Breaking them into smaller, logically-grouped collections before conversion typically yields the best results.