Online Tool Store
Random File Generator
Generate exact-size dummy files: truly random or zero-filled binary, plain text, valid CSV, or JSON, up to 200 MB — built in your browser, nothing uploaded.
This works right here on your device — nothing gets sent out.
3. Download
Example shown — a 10 KB plain-text file is generated automatically on load.
How the random file generator works
- Set the file size and unit (Bytes, KB, MB, or GB), or tap a common size from 1 KB to 100 MB. The exact byte count appears under the field — 1 KB is 1,024 bytes.
- Choose a file type: plain text, random binary, zero-filled binary, CSV, or JSON.
- Optionally rename the file under Advanced settings, then click Generate file to build it locally in your browser at exactly that size.
- Click Download to save the generated file — requests above 200 MB are automatically capped so generation stays fast.
FAQ
What does this tool do?
Creates downloadable dummy files — plain text, random binary, zero-filled binary, CSV, or JSON — at an exact byte size from 1 byte up to 200 MB, for upload, storage-limit, and parser testing.
Does it run in my browser?
Yes. The widget runs locally in your browser without an account, and nothing you generate is uploaded anywhere.
What's the maximum file size I can generate?
Up to 200 MB per file, generated entirely in your browser's memory. Larger requests are automatically capped so generation stays fast — a status message tells you if that happened.
Can I select GB as the unit?
Yes, GB is available alongside Bytes, KB, and MB. The actual output is still capped at 200 MB, which keeps the tool responsive rather than freezing the tab on very large in-memory files.
Is the file exactly the size I asked for?
Yes, to the byte, for every file type. 10 KB produces a 10,240-byte file, because the tool uses 1 KB = 1,024 bytes and shows the exact byte count under the size field before you generate.
Is the random binary file truly random?
Every byte comes from your browser's crypto.getRandomValues, with nothing repeated, so compression cannot shrink it. That makes it the right choice for testing upload speeds or storage limits where a compressible file would give a misleading result.
How do I create a file filled with zeros?
Choose Zero-filled binary (.bin). Every byte is 0x00, which is useful for disk and transfer tests where you want the file to compress to almost nothing.
Are the CSV and JSON files valid?
Yes. The CSV has a header row and ends on a complete row, and the JSON parses with any standard JSON parser — any space left over to reach the exact size is filled with whitespace, which JSON ignores.
Should I verify the result?
Yes. Treat it as a practical test file and verify it against your specific requirements before relying on it.
How we compare
| Feature | Online Tool Store | PineTools | LDDGO | GenTools |
|---|---|---|---|---|
| Plain text, CSV, and JSON test files, not just raw bytes | ✓ | ✗ | Character ranges only | Text and JSON |
| Random or zero-filled binary | ✓ | Random only | ✓ | Random only |
| Bytes, KB, MB, and GB units | ✓ | ✓ | ✓ | MB only |
| Units stated as 1 KB = 1,024 bytes | ✓ | Not specified | ✓ | ✓ |
All three are solid tools. Online Tool Store's Random File Generator is the one to pick when the file's contents matter as well as its size: valid CSV and JSON, truly random or all-zero binary, and the exact byte count shown before you generate. Files are built in your browser and capped at 200 MB.