Dummy File Generator
Instantly create a test file of an exact size — TXT, CSV, JSON, PDF, PNG or BIN. Perfect for testing uploads, size limits and validation logic. PDF and PNG come out as real, openable files.
How it works
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Pick a format
TXT, CSV, JSON, PDF, PNG or BIN
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Set the exact size
Type a number or tap a preset
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Download
Built in-browser, saved instantly
Byte-exact sizes
Generate a file of the precise size you request — great for hitting upload limits like exactly 5 MB.
Real, openable files
PDFs get a valid xref table & trailer, PNGs get correct chunk checksums — so they actually open.
Private & offline
Everything runs in your browser. No uploads, no servers, no tracking — works offline too.
Frequently asked questions
Yes. The PDF is built with a proper cross-reference table and trailer, and the PNG is a real image with correct CRC checksums on every chunk. The requested size is reached with ignored padding (a PDF comment and a PNG tEXt chunk), so the files remain fully openable in standard viewers.
No. The file is generated entirely in your browser using the Blob API and downloaded directly. Nothing is ever sent to a server.
Up to 1 GB. Large files are built in memory, so very large sizes depend on your device's available RAM.
Valid PDF and PNG files have a minimum structure (a few hundred bytes). If you request a size below that minimum, the file is emitted at its smallest valid size and the tool tells you the resulting byte count.
Testing file-upload forms and size limits, checking storage quotas, simulating slow downloads, load-testing, QA of validation logic, and demos where you just need a file of a specific size and type.