Generate fake data for testing
Create a table for specified columns using clearly fictional strings and reserved domains.
Choose count and columns
Per-column settings
Test data with missing/duplicate values
Sequential numbers and UUIDs are never blank. Duplicate rows are for testing input validation and deduplication.
Generation result
After generation, you can preview the first 100 rows in a table.
Safe format for generated data
| Column | Example output | How to distinguish from real data |
|---|---|---|
| Name | Test Last 0042 Test First 0042 | Include “test” in all records |
| test-user-0042@example.com | Example domains reserved for documentation and testing | |
| Address-like | 123 Test St, Sample City, Test Prefecture | Use ‘fictional’ and ‘test’ instead of real prefectures |
| Sequence number | TEST-000042 | Prefix to distinguish from production IDs |
Generated data is created only within your browser.
What the dummy data generator can do
Generate up to 5,000 rows without using real information, including sequential numbers, fictional names, email addresses using reserved domains, fictional address-like strings, dates within a specified range, and UUID v4. Copy or save as CSV, TSV, JSON, or JSON Lines.
Mix in blank cells and duplicate rows at specified rates to test required-field validation, deduplication, import, list display, search, pagination, and more. Generation and file creation happen entirely in your browser; no data is sent to any server.
Names clearly not real
Combine ‘Test Last’ and ‘Test First’ with sequential numbers; do not generate real personal names.
Safe email domains
Only use example.com, example.net, and example.org, which are reserved for illustrative purposes.
Output CSV and JSON with same columns
Preserve the order of selected columns and correctly handle CSV quotes, newlines, and JSON UTF-8 strings.
Missing/duplicate testing
You can also blank out cells except for sequential numbers and UUIDs, and duplicate the previous row to test error cases.
Steps to create test dummy data
- Enter the required quantityUse 20–100 rows for screen checks; increase as needed for pagination or performance tests.
- Select columns to generateMatch system field names and types; omit unnecessary personal-looking columns.
- Set sequence, date, and domainUse prefixes that won’t collide with production IDs, the test period, and example domains.
- Add blanks/duplicates if neededSeparate normal-case data into its own file, and define expected errors before use.
- Preview and saveVerify column names, leading zeros, date formats, and character encoding, then load only into test environments.
Why not use real data in tests
Copying real customer, employee, or vendor names, emails, and addresses into development or verification environments expands the potential exposure through access rights, backups, logs, screenshots, and sharing with contractors. Do not use real data even for display-only purposes.
This tool’s address-like strings use clearly fictitious expressions such as ‘Fictional Prefecture’ and ‘Test City.’ It does not generate postal codes, phone numbers, national ID numbers, credit card numbers, or other numbers that carry a high risk of misdelivery or misidentification.
Why example.com is safe
example.com, example.net, example.org is a domain reserved for documentation, explanation, and testing. Using it reduces the risk of accidental misdelivery to third parties compared to randomly generating domains that ordinary users might register.
However, if your test environment has email-sending capabilities, disable the sending process itself or restrict it to a controlled environment that suppresses incoming mail managed by your organization. Do not rely solely on the domain name; verify settings that prevent external sending.
When to use UUID, sequence, or date
| Field | Use case | Note |
|---|---|---|
| UUID v4 | API IDs, distributed data, and identifiers that resist duplicates | Does not reflect order or creation time |
| Sequence number | Check list order, fixed widths, and Excel leading zeros | Add prefix to distinguish from production IDs |
| Date | Date range search, sorting, deadline display | Generate in YYYY-MM-DD format without time or timezone |
How to choose between CSV, TSV, JSON, and JSON Lines
| Format | Recommended use | Checkpoint |
|---|---|---|
| CSV | Excel, spreadsheets, and common imports | Commas, quotes, UTF-8 BOM, and leading zeros |
| TSV | Tables with many commas in cells, pasting | Quoting values with tabs |
| JSON | APIs, JavaScript, and configuration data | Array, type, character encoding |
| JSON Lines | Logs, line-by-line processing of large data | One object per line, no trailing commas |
Cautions when including missing/duplicate values
The blank rate applies independently to each cell except for sequential numbers and UUIDs. The duplicate rate copies the value from the immediately preceding row, but sequential numbers and UUIDs remain new values, so this creates data that tests duplicates in business fields rather than fully duplicate rows.
For precise boundary-value testing, design expected conditions individually, such as maximum character length, minimum values, invalid dates, control characters, and emoji. This tool provides a foundation for general list and import testing; it does not automatically design test cases from system specifications.
Processing that does not send generated data
Random numbers, names, email- and address-like strings, dates, UUIDs, sequential numbers, blanks and duplicates, and CSV/JSON creation all run in your browser. Generated content is not sent to or stored on WiseChecker servers or external APIs. Reloading the page clears the results.
Dummy data generator FAQ
Are the generated names and addresses real?
Generate clear test strings containing ‘test’ and ‘fictional’ instead of real names or prefectures.
Can emails reach third parties?
Use reserved example domains. However, also disable external sending in the test environment.
Can UUIDs duplicate?
UUID v4 uses cryptographic randomness, making duplicates extremely unlikely, but it is not an absolute theoretical guarantee.
Can the same data be reproduced?
No. ‘Regenerate with same settings’ uses new random numbers. If you need fixed data, keep the saved file.
Can I generate more than 5,000 records?
The limit is 5,000 records to reduce browser load. For large-scale performance tests, use a dedicated script.
Is generated data sent to a server?
Not sent. Processed entirely in your browser.