Building a frontend before the backend exists? Writing tests that need realistic payloads? API Response Mock Generator turns one sample JSON object into endless realistic mock data — names, emails, prices, dates and UUIDs included.
API Response Mock Generator
Turn one sample JSON object into thousands of realistic mock records.
Runs entirely in your browser — nothing is uploaded.
About API Response Mock Generator
Features
- Type-aware generation: strings, numbers, booleans and null handled correctly.
- Smart fields: id, name, email, city, date, price get realistic values.
- Nested support: objects and arrays of objects are generated recursively.
- 1 to 10,000 records in one click.
- JSON, JS object, or JSON array output formats.
- Seed option for reproducible results.
How to Use
- Paste a sample JSON object that shows the shape of your API response.
- Choose record count (1–10,000) and output format.
- Generate — realistic mock data appears instantly.
- Copy or download the result.
Examples
Example 1 — Frontend prototyping. A UI developer generates 50 fake users to build a dashboard before the API exists.
Example 2 — Unit tests. A test engineer mocks a paginated API response with consistent, unique IDs.
Example 3 — Demos. A product manager fills a mock catalog with realistic product names and prices for a demo.
Example 4 — Load testing. A QA engineer generates 1,000 records to test list rendering performance.
Benefits
- Instant: thousands of records generated in milliseconds.
- Realistic: output looks like genuine production data.
- Flexible: any JSON shape works, including nested structures.
- Reproducible: use a seed for the same data every time.
- Private: nothing leaves your browser.
Frequently Asked Questions
How do I generate a mock API response?
Paste any sample JSON object — for example a single record from your API — and choose how many records to generate. The tool fills string, number, boolean and array values with realistic random data.
How does it know what data to generate?
It infers the type from each value in your sample. Strings become realistic text (names, emails, cities, words), numbers become random values in a similar range, booleans become random true/false.
Can I keep certain fields unchanged?
Yes. Fields named id, _id, uuid, createdAt, updatedAt, timestamp and similar keep their special semantics — or their exact value when the option is enabled. IDs always stay unique.
Is the generated data random?
Yes — every field is filled with random but realistic values, so each generated record differs while looking like real data.
What does it support?
Nested objects, arrays of objects, arrays of primitives, all JSON types, plus smart fields like id, name, email, date, price and count. Thousands of records can be generated instantly.
Is my data uploaded?
No. The generator runs entirely in your browser.