OpenAPI Converter
Convert an OpenAPI 3 JSON or YAML file into a more permissive testing specification, change where parameters are declared, or combine both transformations.
Use The OpenAPI Converter
Load an OpenAPI 3 specification, optionally expand its documented coverage, choose how Path Item parameters are declared, and then copy, download, or open the resulting specification. All conversion happens in your browser.
Load OpenAPI Spec
Load a JSON or YAML specification from a URL, or choose a local file.
Expand OpenAPI Coverage
Choose how broadly the converter should relax validation rules and add operations for exploratory testing. Leave No expansion selected to preserve the loaded operation coverage.
Operation-Level vs Shared Path Configuration
Evaluate whether selected parameters are shared on each Path Item or repeated on operations, then keep or convert their placement.
Converted OpenAPI Spec
Select an expansion or placement transformation to generate JSON that can be copied or downloaded. With no transformation selected, the original specification remains available to the embedded clients.
Load an OpenAPI JSON or YAML file, then choose a conversion.
Open in Embedded Client
Open the original OpenAPI file, or the converted file when a transformation is selected, in one of the embedded API clients on this site.
Convert OpenAPI Specifications In Your Browser
Strict OpenAPI files are useful documentation, but they can also limit testing. A schema might require a field, restrict a value to an enum, hide an unsupported HTTP method, or stop Swagger UI and REST clients from making the unusual request you want to investigate.
This browser tool converts an OpenAPI 3 file into a less restrictive tester specification, changes its parameter placement, or does both. The conversion happens in your browser. Local files are not uploaded to API Challenges.
The output is useful for exploratory API testing, negative testing, contract comparison, and importing a more flexible API description into tools that can read OpenAPI files.
Create Practical Or Aggressive OpenAPI Testing Files
The Practical profile removes common schema validation restrictions and adds the common REST methods: GET, POST, PUT, PATCH, DELETE, OPTIONS, and HEAD. Use it when you want a less restrictive file that still feels close to a normal REST API contract.
The Aggressive profile applies the same relaxation and adds every selectable OpenAPI method to every path, including TRACE. It also adds loose JSON request bodies to generated body-capable operations. Use it when you want to push an API harder and see how the real server behaves outside the documented happy path.
Choose Custom when you want to decide exactly which validation rules to remove and which HTTP methods to add.
Move Shared And Operation-Level Parameters
OpenAPI parameters can be shared by every operation on a Path Item or declared directly on each operation. Evaluate the loaded specification to see whether its selected parameters are shared, operation-level, mixed, or absent. Convert toward either placement while preserving operation-level overrides.
Use URL path parameters for parameters associated with {name} segments. Use All Path Item parameters when shared query, header, and cookie parameters should move as well.
Download A Less Restrictive OpenAPI File For REST Client Testing
After conversion, copy the JSON or download the tester OpenAPI file. You can import the converted file into REST clients that support OpenAPI, or use it as a reference while sending requests with the Basic Client.
For more tool options, compare the REST/HTTP client summary reviews, read the REST/HTTP Clients overview, or review detailed notes for Bruno, Postman, Insomnia, and cURL.
Use Converted OpenAPI Files In Embedded Clients And REST Clients
Use the Open in Embedded Client buttons to render the loaded OpenAPI file in Swagger UI, OpenAPI Explorer, Scalar, Stoplight Elements, Zudoku, or Redoc. When a transformation changes the specification, the embedded client opens the converted result; otherwise it opens the original URL or local file content.
If this is your first time using OpenAPI or REST clients, follow How to Test REST APIs, the API Simulator Walkthrough, the Swagger UI and Tools guide, or the OpenAPI for API Testing reference first.
For examples of standard and less-validating OpenAPI files generated by this site, compare the API Challenges OpenAPI Files, API Simulator OpenAPI Files, Simple API OpenAPI Files, and Buggy API OpenAPI Files.
CORS Limits For Browser OpenAPI Conversion
Because this converter runs in the browser, URL loading is limited by CORS.
CORS means Cross-Origin Resource Sharing. It is the browser rule that controls whether JavaScript from one origin can call another origin. If the OpenAPI URL does not allow this site, the browser may block loading the file. Download the file and open it from disk if the server does not allow browser access.
The converted file can describe methods such as TRACE, but browsers may still block some methods or requests when you try them from Swagger UI. Use a desktop REST client, command line client, or HTTP proxy when you need to avoid browser limits or inspect raw traffic.