API Mock Data Generator — Realistic JSON Builder
Generate structured, realistic mock data for API endpoint testing. Define fields with names and types — UUID, name, email, integer, enum, date, and more — set how many rows you need, and export as a JSON array, NDJSON, or CSV. All generation runs entirely in your browser with no data sent to any server.
How to Use API Mock Data Generator — Realistic JSON Builder
How to Use the API Mock Data Generator
Step 1: Set Row Count and Format
Rows — Enter how many records to generate (1–500). Use the quick presets (5, 10, 25, 50) or type a custom value.
Output format — Choose how the data is structured:
- JSON Array — A single
[{...}, {...}]array, ideal for seeding databases or mocking REST responses. - NDJSON — Newline-delimited JSON, one object per line. Used by log pipelines, Elasticsearch bulk imports, and streaming APIs.
- CSV — Comma-separated values with a header row. Open in Excel, import into databases, or use with data analysis tools.
Step 2: Load an Example Schema (Optional)
Click one of the example schema buttons to pre-fill the field list with a realistic starting point:
- User — id, firstName, lastName, email, phone, role (enum), isActive, createdAt
- Product — id, name, category (enum), price, stock, rating, inStock, createdAt
- Order — orderId, customerId, status (enum), total, itemCount, city, country, createdAt
- Log Entry — id (increment), level (enum), service (enum), message (sentence), ipAddress, duration, timestamp
Step 3: Define Your Fields
Each field has a Name and a Type. Optionally configure type-specific options where shown.
Available field types:
ID & System
- UUID v4 — Standard UUID, e.g.
550e8400-e29b-41d4-a716-446655440000 - Auto Increment — Sequential integers. Options: start value (default 1)
- Boolean —
trueorfalse
Numbers
- Integer — Whole numbers. Options:
min,max(e.g.1,100) - Float — Decimal numbers. Options:
min,max(e.g.0,1) - Price — Two-decimal currency value. Options:
min,max(e.g.5,500)
Person
- First Name, Last Name, Full Name — Realistic English names
- Username — e.g.
johnsmith42 - Email — e.g.
john.smith@gmail.com - Phone Number — US format:
+1-555-123-4567
Location
- Street Address, City, Country, Zip Code
Business
- Company, Job Title
Internet
- URL — e.g.
https://alpha.io - IP Address — e.g.
192.168.1.42 - Hex Color — e.g.
#a3f2c1
Date & Time
- Date — ISO date string (YYYY-MM-DD). Options:
start,enddate range - Date + Time — ISO datetime string. Options:
start,enddate range - Unix Timestamp — Seconds since epoch
Text
- Random Word — NATO phonetic or common word
- Sentence — Random 6–12 word sentence
Custom
- Enum — Pick randomly from your list. Options: comma-separated values (e.g.
active,inactive,pending)
Step 4: Generate and Export
Click Generate N Records. The output appears instantly in the right panel.
- Copy — Copy all output to clipboard
- Download — Save as
.json,.ndjson, or.csvfile - Re-generate — Click Generate again to get a new random dataset with the same schema
Tips
- Field names support any string — use camelCase (
createdAt), snake_case (created_at), or any convention that matches your API - Use Enum for status fields, categories, or any fixed set of values
- Use Auto Increment for sequential IDs when you need predictable order
- Combine UUID for
idand dateTime forcreatedAtto match common REST API patterns
Frequently Asked Questions
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