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
Most Viewed Tools
Screen Size Converter — Diagonal Dimension Tool
Calculate screen width and height from diagonal size and aspect ratio. Convert between inches and centimeters for displays, TVs, and monitors with instant dimension calculations.
Use Tool →DPI Calculator — Print Resolution Tool
Calculate DPI (dots per inch), image dimensions, and print sizes. Convert between pixels and physical dimensions for printing and displays.
Use Tool →Seconds to Time Converter — HH:MM:SS Formatter
Convert seconds to HH:MM:SS time format instantly with precise calculations and easy-to-read formatting.
Use Tool →TOTP Code Generator — 2FA Testing Tool
Generate time-based one-time passwords from a TOTP secret key. Enter your base32 secret, choose a period and digit length, and get the current and next codes with a live countdown timer. Useful for testing and debugging 2FA integrations.
Use Tool →Password Entropy Calculator — Crack Time Estimator
Calculate the information-theoretic bit entropy of any password or API key. Detects character set pools automatically, shows the total number of possible combinations, and estimates crack time across five attack scenarios from rate-limited web logins to GPU cracking clusters.
Use Tool →JSONL Formatter — Line-by-Line Validator
Format, validate, and inspect JSON Lines (JSONL) and NDJSON files. Validates each line individually, reports parse errors by line number, outputs compact JSONL or a pretty-print preview, and lets you download the cleaned file.
Use Tool →JSON to Zod — Schema Generator
Generate Zod validation schema code from a JSON sample object. Infers z.string(), z.number(), z.boolean(), z.array(), z.object(), and z.null() types automatically. Handles nested objects, arrays of objects with optional field detection, and outputs copy-ready TypeScript with import and z.infer type alias.
Use Tool →TLS Cipher Suite Checker — Strength Analyzer
Check TLS protocol version compatibility and cipher suite strength ratings against current best practices. Supports IANA and OpenSSL cipher names — rates each suite as Strong, Weak, or Deprecated and explains why.
Use Tool →Related API & Backend Tools
CORS Header Generator — Cross-Origin Config Tool
Build CORS configuration headers interactively for web servers and APIs. Set allowed origins, methods, request headers, credentials, and preflight cache duration — then copy the generated Access-Control headers or ready-to-paste code snippets for nginx, Express.js, Flask, and .NET.
Use Tool →API Gateway Rate Limiting Calculator — Model RPS, Burst, and Token Buckets
Calculate token bucket size and refill rate from RPS targets for API gateway throttling. Enter your steady-state requests per second, burst multiplier, and average response time — the calculator outputs the bucket capacity, refill rate, per-minute and per-hour quotas, and concurrent connection estimate. Generates ready-to-paste throttling config for AWS API Gateway, Kong, and Nginx. Free and runs entirely in your browser.
Use Tool →API Latency Budget Calculator — Plan Distributed System Performance
Set a P99 SLO latency target and distribute the budget across your upstream service dependencies. See remaining headroom, utilization percentage, a stacked allocation bar, and a per-service breakdown with optional P99 actual measurements.
Use Tool →GraphQL Subscription Builder — Generate WebSocket Payloads and Client Queries
Build GraphQL subscription query strings and generate WebSocket connection code snippets for Apollo Client, urql, and graphql-ws. Define your operation name, variables, and selection fields visually, then copy the ready-to-use code.
Use Tool →GraphQL Cost Estimator — Analyze Query Complexity and Depth
Assign custom field weights to a GraphQL schema and calculate the total query complexity score. Paste any GraphQL query, configure per-field costs, and get a per-field breakdown table showing depth, multipliers, and cumulative cost.
Use Tool →OAuth Token Validator — JWT & OIDC Decoder
Validate and inspect OAuth tokens in your browser. Decode JWT access tokens and ID tokens to view claims, scopes, and expiry. Analyse opaque tokens for entropy and format. Free and private.
Use Tool →Postman to OpenAPI Converter — Spec Migration Tool
Convert Postman Collection v2.1 JSON to OpenAPI 3.0 specification format. Upload or paste your collection, and get a downloadable openapi.yaml or openapi.json with mapped paths, parameters, request bodies, and example responses.
Use Tool →OAuth PKCE Generator — Create Secure Code Verifiers and Challenges
Generate RFC 7636 PKCE code verifier and challenge pairs for OAuth 2.0 authorization code flow. Choose verifier length, get the SHA-256 code challenge, and see exactly where each value goes in the auth URL and token exchange request.
Use Tool →Share Your Feedback
Help us improve this tool by sharing your experience