Random File Generator
Create dummy files for upload, storage, or download checks. Choose an exact byte size, file type, quantity, and filename style.
Use % where each file number should appear, such as sample-%.
Up to 10 MB per file and 20 MB total. 1 KB = 1,000 bytes; 1 MB = 1,000,000 bytes.
Set file options and generate local test files.
A QUICK WALKTHROUGH
How to use this tool
- Choose a size and unit, file type, and number of files.
- Select random, numbered, or custom filenames. Use % in a custom pattern to insert each file number.
- Generate files, then download them individually or together as a ZIP archive.
File types and exact sizes
Binary files contain secure random bytes. Text files contain printable ASCII. CSV files contain one row of random ASCII fields. JSON files contain one valid JSON string value. B and KB and MB use decimal byte sizes: 1 KB is 1,000 bytes and 1 MB is 1,000,000 bytes. JSON files need at least 2 bytes.
Names and batches
Generate one to ten files using random names, numbered names, or a custom pattern. In a custom pattern, each % is replaced with that file’s sequence number; a % is required when creating multiple custom-named files. File names are sanitized to remove path separators and control characters.
Local, with memory limits
File bytes and ZIP archives are created in this browser and are not uploaded. Each file is limited to 10 MB and the combined batch to 20 MB. Web Crypto is required for random content; there is no weak-randomness fallback.
A test-data tool
Generated files are synthetic fixtures for capacity and transfer checks, not useful documents or a source of passwords, keys, or other security secrets.
GOOD TO KNOW
Common questions
Are the chosen sizes exact?
Yes. The generated file’s byte length equals the entered size after converting B, KB, or MB using decimal units.
Can I create several files at once?
Yes. Create one to ten files, download each separately, or download the whole batch as a ZIP.
Is JSON output valid JSON?
Yes. It is one JSON string value and must be at least 2 bytes to include its opening and closing quote.
Are files uploaded?
No. File contents and ZIP archives are generated locally in your browser.