Overview
Introduction
Real files sometimes arrive corrupted: a bad download, a flaky storage medium, or a botched transfer, and code that assumes clean input can fail in confusing ways when that happens.
This tool intentionally corrupts text so you can test that failure path on purpose, before it happens for real.
What Is File Corruptor?
A text corruption simulator that randomly replaces a percentage of characters in the input with noise, approximating what bit rot or a partial transfer failure looks like in a text file.
It runs entirely in your browser; nothing is uploaded.
How File Corruptor Works
The input is split into individual characters, and a target count is computed from the corruption percentage (rounded up to at least one character for any nonzero percentage).
That many distinct positions are chosen at random and each is overwritten with a randomly chosen noise character from a small punctuation-and-symbol set, then the characters are rejoined into the output.
When To Use File Corruptor
Use it to test how a parser, file importer, or validation layer behaves when handed damaged input, does it fail gracefully with a clear error, or does it crash or silently produce wrong output.
It's also useful for demoing error-handling UI without needing to track down a genuinely corrupted file.
Often used alongside Text File Generator and Text File Truncator.
Features
Advantages
- Quickly produces realistic-looking corrupted text for testing.
- Adjustable corruption intensity via a single percentage.
- No need to hunt down or manually edit a real corrupted file.
Limitations
- Corruption is random each run, not reproducible from a seed, so it's better suited to exploratory testing than regression tests that need identical output.
- It corrupts individual characters uniformly at random, which doesn't model every real-world corruption pattern (e.g. a corrupted contiguous block rather than scattered bytes).
Examples
Best Practices & Notes
Best Practices
- Start with a low percentage (5-10%) to test graceful degradation before jumping to heavily corrupted input.
- Use Create a Random Text File first if you need a larger sample file to corrupt.
- Re-run at the same percentage a few times, since the random positions change each run and can reveal different edge cases.
Developer Notes
Corruption positions are tracked in a Set to guarantee each targeted character is touched at most once, so a requested percentage always maps to that many distinct corrupted positions rather than allowing duplicate hits to under-corrupt the output.
File Corruptor Use Cases
- Testing a file parser's error handling against damaged input
- Demoing how an application surfaces a corrupted-file error to users
- Stress-testing an import pipeline with a range of corruption intensities
Common Mistakes
- Treating the output as reproducible; the same input and percentage will corrupt different positions each time.
- Setting the percentage too high and concluding a parser is broken, when 80-100% corruption would defeat almost any format.
Tips
- Pair with Slice a Text File to corrupt only a specific section of a larger file, leaving the rest intact.
- If your test needs a fixed, repeatable corrupted file, download one result and reuse that saved file rather than regenerating it each time.