Corrupt file generator | Create Realistic File Errors

Generate corrupted files in various formats for testing. Upload any file and set the corruption level to simulate issues for software testing or pranks. Create unusable files that look normal, ideal for developers and testers.

Types marked with * get a real file signature.
test-file.pdf
Any type works. Up to 512 MB.
Your file is never uploaded. It is read and damaged inside your browser, on your own device, and the copy is saved straight to your downloads. Nothing reaches us, which is also why there is no small size limit here.

Why these files behave like genuinely damaged ones

A file made of random bytes from beginning to end is rejected before your software really looks at it, so it tests almost nothing. This tool writes the genuine signature for the type you picked and fills the rest with garbage. Your operating system still shows it as a PDF, a ZIP or an MP4, the application still opens it, reads the header, and only then hits the damage. That is the path a real corrupted file takes, and it is the one worth testing.

What is a corrupt file generator?

A corrupt file generator produces a deliberately unreadable file so you can see how software copes with damaged input. You can either build one from scratch at any size and type, or upload nothing at all and have this page damage a copy of a file you already have, right in your browser.

How to use it

  1. Pick a mode: build a broken file from scratch, or damage a copy of one of your own.
  2. To build one, set the size and unit, name it, and choose the file type.
  3. Leave the signature switch on so the file is still recognised as that type.
  4. To damage your own file, choose it and pick how heavy the damage should be.
  5. Download the result. The original file on your machine is never touched.

What it is for

  • Checking that your app shows a clear error instead of crashing on a bad file.
  • Testing upload limits and validation with files of an exact size.
  • Confirming that backup and recovery tools actually detect damage.
  • Filling storage to a known size while testing capacity or quotas.
  • Teaching what file corruption looks like without risking real data.

Which mode to use

If you want toUse
Test how your app handles a damaged PDF, ZIP or videoGenerate, with the signature switch on
Break a specific document you already haveCorrupt a file I have
Fill a disk or hit an exact upload sizeGenerate, any type, signature optional
Check whether a repair tool can still rescue a fileCorrupt a file I have, Light

This tool is for testing software. Please do not pass a damaged file off as work you were meant to deliver.

Frequently asked questions

No. Both modes run entirely in your browser. The file you choose is read on your own device, a damaged copy is built there and saved straight to your downloads. Nothing is sent to us, which is also why the size limit here is far higher than on sites that have to process the file on a server.

Never. You always get a new file with "-corrupted" added to the name. The file you picked is left exactly as it was.

Light scrambles roughly one percent of the bytes and leaves the length alone, which is often enough for a repair tool to recover. Medium scrambles about a tenth and cuts the end off, which usually cannot be repaired. Strong rewrites around a third of it and removes a quarter. Pick the lightest one that still breaks what you are testing.

Those bytes are the file signature, the part your operating system reads to decide what the file is. Keeping them means the file is still treated as a PDF or a ZIP and the application opens it before discovering the damage, which is what you usually want to test. Turn the switch off if you want to see what your software does when it cannot even tell what the file is.

Around fifty common types across documents, images, audio, video, archives, disc images, design files and developer formats. You can also type any extension you like, or generate a file with no extension at all. Types that get a genuine signature are marked with an asterisk in the list.

Up to 2 GB when generating, and up to 512 MB when damaging one of your own. Both limits are about your browser memory rather than any server, so a large file will take a moment and use a fair amount of RAM while it is being built.

That is the point: it should open far enough to fail. With the signature kept, the application recognises the type, starts reading, and then hits content that makes no sense. What it does next, a clear error message or a crash, is exactly what you are testing.

Making a broken file for testing is entirely ordinary, and it is what this page is for. Handing one to someone to make them believe you delivered work you did not do is a different matter, and not something we can help with.

What is a corrupt file generator?

A corrupt file generator produces a deliberately unreadable file so you can see how software copes with damaged input. You can either build one from scratch at any size and type, or upload nothing at all and have this page damage a copy of a file you already have, right in your browser.

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