mock-api
A mock API is a fake server that returns predefined JSON responses for development and testing — letting front-end teams work before the real backend is ready. The ZTools Mock API generator builds the response payload itself: define a JSON schema (fields, types, example values, optional arrays), pick the row count, and the tool fills the structure with realistic faker-style data (names, emails, dates, lorem text, IDs, prices). Output is a JSON document or an array of objects you can paste into a service worker, msw config, json-server seed file, or a static fixture in your test suite.
Use cases
Front-end development before backend is ready
API contract is signed; backend ETA is two weeks. Generate the expected JSON structure with realistic data, paste into msw, build the UI against it.
Storybook fixtures
Each story needs sample props. A mock generator gives consistent, realistic data without hand-typing 30 user objects.
Unit-test seeds
Tests need predictable data. Generate once, save as a JSON fixture, import everywhere.
Demo / sales presentations
A live demo needs a populated UI. Mock data avoids embarrassing empty states without using real customer data.
How it works
- Define schema — Add fields (name, email, age, isActive, createdAt). Pick a type (string, number, boolean, date, enum, nested object, array of objects).
- Pick generators — Each field can use a generator: full-name, email, lorem-paragraph, integer-range, date-range, uuid, sequential-id, or fixed value.
- Set count — Generate 1, 10, 100, or 10,000 rows. Output is an array of objects matching the schema.
- Copy JSON — One-click copy. Or download as .json. Use directly in msw, json-server, mirage, or as a static fixture.
Examples
Input: Schema: { id: uuid, name: full-name, email: email, age: integer 18-65 }; count 3
Output: Output: [{id:"a1...", name:"Jane Cooper", email:"jcooper@example.com", age:34}, ...] — three randomly-generated user records.
Input: Nested: { user: { id, name }, posts: array of { title, body } size 2 }
Output: Each top-level row contains a user object and an array of two post objects — matches a typical "user with relations" API response.
Input: Sequential IDs from 1
Output: Useful when test code assumes incrementing IDs. Toggle "sequential" instead of "uuid".
Frequently asked questions
Is this a mock server or just a generator?
Generator. Output is a JSON document. To serve it as an HTTP API, paste into msw (in-browser), json-server (Node), or mockoon. The generator gets you 80% of the way; the server piece is one extra step.
How realistic is the data?
Names from common Western lists; emails follow firstname.lastname@example.com pattern; dates within a configurable range. Realistic for dev/demo; not statistically representative of any real population.
Can I seed for reproducibility?
Yes — provide a seed; same seed + same schema = same output. Useful for tests where consistency matters.
Does it support GraphQL?
JSON only. For GraphQL, use the JSON output as a resolver mock — schema-aware GraphQL mocking needs a tool like @graphql-tools/mock.
Privacy?
All generation in the browser. The schema and generated data never leave your device.
Faker.js compatibility?
Generator names align with Faker.js where possible (name.fullName, internet.email, lorem.paragraph). Migrating to Faker later is a search-replace.
Tips
- Define the schema once, reuse across tests. A 30-line schema beats 200 lines of hand-written fixtures.
- Use sequential IDs (1, 2, 3) when assertions reference IDs; use UUIDs when uniqueness across runs matters.
- For demo screenshots, generate names from a wide cultural pool — single-locale data looks artificial.
- Pair with msw (Mock Service Worker) to serve mocks during front-end dev without standing up a Node server.
Try it now
The full mock-api runs in your browser at https://ztools.zaions.com/mock-api — no signup, no upload, no data leaves your device.
Last updated: 2026-05-06 · Author: Ahsan Mahmood · Edit this page on GitHub