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偽のテストデータジェネレーター（JSON / CSV）

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Fake Test Data Generator

Generate realistic fake test data with a custom schema. Define your fields (names, emails, UUIDs, addresses, dates, and more), set the row count, and export as JSON, CSV, or NDJSON. Everything runs in your browser — no server processing, no data leaves your machine.

使い方

Build your schema using the field editor: add fields with names and types (First Name, Email, UUID, Phone, Date, Integer, Boolean, etc.). Set the number of rows to generate (1-1000), choose your output format (JSON Array, CSV, or NDJSON), and click Generate. Preview the data in the output area, then download the file or copy to clipboard. Start with the default schema (id, name, email) and customize from there.

特徴

21 Field Types — First Name, Last Name, Full Name, Email, UUID, Phone Number, Date, Integer, Decimal, Boolean, URL, IPv4 Address, Company Name, Street Address, City, Country, Zip Code, Hex Color, Username, Lorem Ipsum paragraph, and Custom List (your own comma-separated values).
Dynamic Schema Editor — Add, remove, and name fields freely. Start with sensible defaults (id, name, email) and build your exact data structure.
3 Export Formats — JSON Array (pretty-printed), CSV (with header row, properly escaped), and NDJSON (newline-delimited JSON, one object per line).
Up to 1,000 Rows — Generate anywhere from 1 to 1,000 rows of test data instantly in the browser.
Preview Before Download — See the generated data in a scrollable preview before committing to download. Shows first 100 rows for large datasets.
Download & Copy — Download as .json, .csv, or .ndjson file, or copy the full output to clipboard.
リアルなデータ — Names, emails, addresses, companies, and other fields generate realistic-looking values using built-in data pools — no external libraries required.
Custom Lists — Need a field with specific values (status codes, product types, categories)? Use the Custom List type with your own comma-separated options.

Supported Field Types

Identity: First Name, Last Name, Full Name, Username, Email
Technical: UUID (v4), IPv4 Address, URL, Hex Color
Contact: Phone Number, Street Address, City, Country, Zip Code
Business: Company Name
Data: Integer, Decimal, Boolean, Date
Text: Lorem Ipsum paragraph
Custom: Your own comma-separated value list

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What is fake test data used for?

Fake test data is essential for software development, testing, and demonstrations. Developers use it to populate databases during development, test application performance with realistic data volumes, create demo environments for stakeholders, validate data processing pipelines, and test import/export features. Using fake data instead of real data protects privacy and avoids compliance issues (GDPR, HIPAA). This tool generates data entirely in your browser, so nothing is sent to any server.

What is the difference between JSON, CSV, and NDJSON?

JSON Array wraps all records in a single JSON array — ideal for APIs, JavaScript applications, and NoSQL databases. CSV (Comma-Separated Values) uses a header row followed by data rows — perfect for spreadsheets (Excel, Google Sheets), database imports, and data analysis tools. NDJSON (Newline-Delimited JSON) puts one JSON object per line — used for streaming data, log processing, and tools like jq, Elasticsearch bulk imports, and Apache Kafka. Choose based on where you’ll use the data.

Is the generated data truly random?

The data is pseudo-random — generated using JavaScript’s Math.random() with built-in pools of realistic names, cities, companies, and other values. Each generation produces different results. The data looks realistic (proper email formats, valid UUID structure, correctly formatted phone numbers) but is entirely fictional. No real people, companies, or addresses are represented. UUIDs follow the v4 format standard, and emails are constructed from the generated names.

Can I generate data with specific values for a field?

Yes — use the Custom List field type. Enter your values separated by commas (e.g., ‘active, inactive, pending’ or ‘small, medium, large, xl’). The generator will randomly pick from your list for each row. This is useful for status fields, categories, product types, roles, or any enumerated value. You can mix Custom List fields with built-in types in the same schema.

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