Dev
Mock API Response Generator
Frontend work shouldn't stall because a backend endpoint isn't ready. A mock API response generator lets you produce realistic JSON payloads for five resource types — user, product, order, post, and transaction — so you can build UI components and write tests against real-shaped data immediately. Four inputs control the output. Resource type determines the schema: users get id, name, email, status, and created_at; products get name, category, price, stock, and rating; orders include status, total, and items count; posts include views, likes, and published flag; transactions include type, amount, currency, and status. Count sets how many records appear (1–20). The envelope wrapper option adds success, count, and data layers matching the shape most REST APIs return. JSON Format toggles between pretty-printed and minified output.
Read the complete guide — 4 min read
Added April 2026
How to use
- Choose your options above
- Click Generate
- Copy your result
Detailed instructions
- Select a resource type from the dropdown that matches the data your component or test expects.
- Set the item count to the number of records your UI needs, such as 3 for a card grid or 10 for a table.
- Choose whether to wrap the output in an envelope object for APIs that return a success/count/data structure.
- Click Generate and review the JSON output in the result panel below.
- Copy the output and paste it into your test fixture file, MSW handler, or mock server configuration.
Use Cases
- •Seeding a React user list component with realistic names, emails, and roles before the backend endpoint exists
- •Creating MSW http.get() handler fixtures for Jest or Vitest integration tests using envelope-wrapped JSON
- •Populating Postman mock servers with product and order payloads during API-first design sprints
- •Pasting plausible transaction records into OpenAPI spec example fields for team documentation reviews
- •Demoing a product dashboard to stakeholders using real-looking prices, categories, and stock values
Tips
- →Set count to 1 when mocking a detail endpoint like GET /users/:id, then remove the outer array manually.
- →Generate with the envelope on, then generate again with it off — keep both versions as separate fixtures for list vs. detail routes.
- →Use the order resource type to test conditional UI logic, since its status field cycles through multiple states like pending, shipped, and delivered.
- →When testing responsive layouts, generate 20+ items to surface overflow bugs that a 3-item mock would never trigger.
- →Paste the output into a .json file tracked by your repo so teammates and CI jobs use identical, reproducible test data.
- →For Postman mocks, use the envelope-wrapped version and set the Content-Type header to application/json to match real API behavior exactly.
FAQ
how do I use mock API response output in Jest or Vitest tests
Save the generated JSON as a .json file in your __fixtures__ directory and import it directly — both Jest and Vitest handle JSON imports natively. If you enabled the envelope wrapper, destructure the data key to get the array your component or hook consumes. Use it as the resolved value in a jest.fn().mockResolvedValue() or vi.fn() call.
what does the envelope wrapper option add to the output
Enabling the wrapper nests your records inside a parent object with three keys: success (boolean true), count (matching the number you requested), and data (the array of items). This mirrors the response envelope most REST APIs return, so you can drop it straight into your frontend mock layer without any transformation.
which fields are included for each resource type
User gets id, name, email, status, created_at, and age. Product gets id, name, category, price, stock, and rating. Order gets id, user_id, status, total, and items count. Post gets id, title, author_id, views, likes, and a published boolean. Transaction gets id, type, amount, currency, and status.
can I get minified JSON instead of pretty-printed output
Yes — switch JSON Format to Minified for a single-line, whitespace-free payload ideal for a compact fixture file or simulating a production API response. Pretty keeps the 2-space indentation for reading and debugging.
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