How does this tool generate mock data from OpenAPI schemas?

It parses your OpenAPI specification (JSON or YAML), extracts the response schema for the selected endpoint and status code, resolves all schema references recursively, and populates realistic values according to property types, formats, and enums.

Does it support YAML and JSON formats?

Yes. It supports both YAML and JSON OpenAPI specifications, automatically detecting and parsing your document client-side.

Is my proprietary API specification uploaded to any server?

No. The entire parsing and mock data generation pipeline executes 100% in your local browser sandbox. No API keys, specifications, or schema definitions are transmitted over the network.

QuickCoderHub

Online OpenAPI & Swagger Mock Data Generator

Instantly synthesize realistic mock JSON response payloads from OpenAPI 3.0, 3.1 and Swagger 2.0 schemas. Choose endpoints and status codes, resolve $refs, customize array lengths, and export mocks with zero backend server dependencies.

OpenAPI / Swagger Spec (YAML / JSON)

Ready to parse

Generated Mock Response

ENDPOINT:

STATUS:

ARRAY ITEMS:

// Mock data will appear here...

SIMULATED cURL:

curl -X GET "https://api.example.com/api/v1/pets"

The Advantage of Client-Side OpenAPI Mocking

Modern frontend engineering often requires building user interfaces against API endpoints that are still being designed or implemented by backend teams. Mock data generators bridge this gap by synthesizing realistic data structures according to OpenAPI contracts.

Key Mocking Capabilities

Full Schema Traversal: Recursively follows $ref schema definitions across components without crashing on circular object hierarchies.
Heuristic Field Generation: Automatically recognizes schema formats like uuid, date-time, email, uri, and common field names (e.g., id, avatarUrl, createdAt) to generate meaningful values instead of generic placeholders.
Status Code Branching: Test not only happy path 200 OK / 201 Created responses, but also 400 Bad Request and 404 Not Found error payloads specified in the API contract.