Postman to OpenAPI Converter: Reuse What You Already Have
Teams often accumulate a Postman collection of working API requests long before they have a formal OpenAPI specification — and rewriting that collection into OpenAPI by hand is redundant work. This tool walks your collection's requests (including nested folders), extracts each endpoint's method, path, path parameters, and body schema, and produces a genuine OpenAPI 3.0 document.
Nested Postman folders are recursively flattened; :paramName path syntax converts to OpenAPI's {paramName} syntax.
Handling Postman's URL Formats
Postman represents a request URL either as a plain raw string or as a structured object with a `raw` field and a parsed `path` array — this tool reads the raw form either way, strips the protocol and host, and keeps just the path, converting any `:id`-style path variables into OpenAPI's `{id}` syntax along the way.
Recursively Flattening Folders
A real-world Postman collection is rarely flat — related requests get grouped into folders, which are themselves just items containing more items. The converter recurses through this structure to find every actual request regardless of how deeply it's nested, so no endpoint gets missed because it was inside a folder.
Practical Examples
Migrating an Existing Collection
You have a working Postman collection but need an OpenAPI spec for documentation tooling.
- 1.Paste the exported collection JSON
- 2.Get a matching OpenAPI 3.0 document
- 3.Refine response schemas and additional status codes by hand
What Gets Converted
- Every request, including those nested in folders
- Path, with :paramName → {paramName} conversion
- Path parameters (auto-declared from path placeholders)
- Request body schema (inferred from raw JSON bodies)
Good Use Cases
- Bootstrapping OpenAPI docs from an existing Postman collection
- Feeding a Postman-based workflow into OpenAPI-based tooling
- Migrating away from Postman-only API documentation
- Generating a starting point for a formal API spec
Frequently Asked Questions
How does it extract the path from a Postman request?
It strips the protocol and host from the request URL (whether given as a raw string or Postman's { raw, path } object), keeping only the path portion and dropping any query string — then converts Postman's :paramName path-variable syntax into OpenAPI's {paramName} syntax.
Does it handle nested folders in the collection?
Yes — Postman collections can nest requests inside folders (which are themselves items containing an item array); the converter recursively flattens all folders to find every actual request, regardless of nesting depth.
How is the request body converted?
If a request has a raw JSON body, it's parsed and passed through the same schema-inference logic as the Swagger/OpenAPI Generator tool — building a matching OpenAPI schema object with the original values kept as an example. Non-JSON raw bodies are represented as a generic text/plain schema.
What Postman collection version does this expect?
Collection Format v2.1 (the current standard, identified by info.schema pointing at the v2.1.0 schema URL) — older v1 collections have a different structure and aren't supported.
Is my collection sent anywhere?
No, conversion happens entirely in your browser.