postman-openapi-converter

OpenAPI → Postman Collection Converter

When to Use

Use this skill when you need convert OpenAPI 3.x or Swagger 2.0 specs (YAML or JSON) into complete, import-ready Postman Collection v2.1 JSON files. Use this skill whenever the user provides or references an OpenAPI spec, Swagger file, openapi.yaml, swagger.json, or uses phrases like "convert my OpenAPI spec",...

Converts OpenAPI 3.x or Swagger 2.0 specs into a valid Postman Collection v2.1.

---

Step 1 — Detect & Validate Input

Identify the spec version from the input:

• openapi: 3.x.x → OpenAPI 3
• swagger: "2.0" → Swagger 2

If the input is truncated or partial, convert what's available and note missing sections.

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Step 2 — Extraction Mapping

OpenAPI 3 → Postman

| OpenAPI field | Postman mapping |

|---|---|

| info.title | Collection name |

| info.description | Collection description |

| servers[0].url | {{base_url}} variable |

| paths.<path>.<method> | One request item per operation |

| operationId or summary | Request name |

| parameters (path/query/header) | URL path variables, query params, headers |

| requestBody.content.application/json.schema | Body (raw JSON), generate example from schema |

| responses | Saved example responses |

| components.securitySchemes | Collection-level auth |

| tags | Folder grouping |

Swagger 2 → Postman

| Swagger field | Postman mapping |

|---|---|

| host + basePath | {{base_url}} |

| paths.<path>.<method> | Request item |

| parameters | Query/path/header/body params |

| consumes / produces | Content-Type / Accept headers |

| securityDefinitions | Collection auth |

| tags | Folders |

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Step 3 — Generate Example Bodies

For each request with a requestBody or body parameter, generate a realistic example JSON body from the schema:

• Use property names as keys
• Infer sensible example values from type + format (e.g., "email" format → "user@example.com", "date-time" → "2024-01-15T10:30:00Z")
• For $ref schemas, resolve them inline

---

Step 4 — Auth Handling

Map security schemes to Postman auth:

| OpenAPI scheme | Postman auth type |

|---|---|

| http: bearer | bearer with {{token}} |

| http: basic | basic with {{username}} / {{password}} |

| apiKey: header | apikey header with {{api_key}} |

| apiKey: query | apikey query param |

| oauth2 | oauth2 (note: requires manual token setup) |

Apply auth at collection level if all endpoints share the same scheme. Override at request level for exceptions.

---

Step 5 — Build Collection JSON

Use the standard v2.1 structure (same schema as postman-collection-generator skill).

Key differences for spec-converted collections:

• Always group by tags into folders
• Include description field on each request from operationId + summary + description
• Add saved example responses where responses are defined in the spec

"response": [
  {
    "name": "200 OK",
    "status": "OK",
    "code": 200,
    "header": [{ "key": "Content-Type", "value": "application/json" }],
    "body": "{ \"id\": 1, \"name\": \"example\" }",
    "originalRequest": { <copy of the request> }
  }
]

---

Step 6 — Environment File

Extract all variables into a companion environment:

• base_url from servers[0].url or host + basePath
• token, api_key, username, password as empty placeholders
• Any server variables from servers[0].variables

---

Step 7 — Output

1. collection.json — Full Postman Collection v2.1
2. environment.json — Matching environment file
3. Conversion summary: number of endpoints converted, folders created, auth type detected, any fields skipped or approximated
4. Import instructions

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Edge Cases

• $ref chains: Resolve all $ref pointers inline before mapping
• allOf / oneOf / anyOf: Use the first/primary schema for body generation; note alternatives in description
• Path parameters: Convert {param} to :param in URL path AND add to variable array in url object
• Multiple content types: Prefer application/json; note others in request description
• No operationId: Generate name from METHOD /path (e.g., GET /users/{id} → Get User by ID)

---

Quality Checklist

• [ ] Every paths entry produces at least one request
• [ ] Path params use :param format in Postman URL
• [ ] All $ref resolved — no raw $ref strings in output
• [ ] Auth tokens are {{variables}}, never hardcoded
• [ ] JSON output is valid and importable

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After Completing the API Design

Once the API design output is delivered, ask the user:

"Would you like me to generate API documentation for this design? (yes/no)"

If the user says yes:

• Check if the API Documentation skill is available in the installed skills list
• If the skill is available:
• Read and follow the instructions in the API Documentation skill
• Use the API design output above as the input
• If the skill is NOT available:
• Inform the user: "It looks like the API Documentation skill isn't installed.

You can install it and re-run.

If the user says no:

• End the task here

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Limitations

• Use this skill only when the task clearly matches its upstream source and local project context.
• Verify commands, generated code, dependencies, credentials, and external service behavior before applying changes.
• Do not treat examples as a substitute for environment-specific tests, security review, or user approval for destructive or costly actions.