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Files Corrupter
Corrupt any file in seconds, without uploading it anywhere
A format-aware file corrupter that destroys the structure real parsers depend on, not just a handful of random bytes. Works on PDFs, Office documents, archives, video, audio and images, entirely inside your browser.
- Nothing leaves your device
- Unlimited file size
- Batch processing
- Four damage levels
Upload and corrupt your file
Everything runs locally. Nothing is uploaded, nothing is stored.
Drop files here or browse Any format, any size, multiple files at once
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0Dedicated tools
0Format profiles
0Bytes uploaded, ever
0Free, forever
Pick a tool for your format
Every format has its own profile, tuned to the structures its parsers rely on.
Document Tools
Office documents and PDFs are the formats people most often need broken, and the hardest to break convincingly.
10 toolsCode & Data Tools
Text-based formats have no header to destroy, so scrambling characters just produces different text.
7 toolsMedia Tools
Media formats are built to survive damage: players skip broken regions and image decoders resynchronise after a bad chunk.
7 toolsArchive Tools
Archives are the formats most explicitly engineered against corruption.
5 toolsSystem Tools
Executables and installers are validated before anything runs, which makes their failure modes precise and reproducible.
4 toolsFun Tools
Not everything has to be serious.
2 toolsHow Files Corrupter works
Three steps, no account, no waiting in a queue.
ReadFile API pulls 8 MB slices into memory
RewriteProfile destroys header, index and trailer
ReturnBlob URL hands the copy straight back
Pick a damage level
Standard is right for almost everyone. The engine identifies the format from the extension and magic bytes, then applies that format profile.
Download the result
The corrupted copy is built in memory and offered as a download with the original filename. Your source file is never modified.
Why this corrupter breaks files others leave working
Most online file corrupters overwrite a few dozen random bytes. On a plain text file that is enough. On the formats people actually need to break it usually is not, because those formats are containers built to survive damage.
Format-aware, not random
The engine reads the extension and the magic bytes, picks one of 87 format profiles, and destroys that format's structural landmarks before it touches the payload. Random byte flips usually land inside a compressed stream, which is exactly the damage Word and Acrobat are designed to recover from.
Nothing is uploaded
Files are read with the File API, rewritten in memory and handed back through a Blob URL. There is no upload endpoint in the codebase, so there is no server log with your filename in it, no retention policy to trust and nothing to breach.
Four calibrated levels
Light leaves a file that opens with a warning or renders partially, which is what produces glitch art. Standard makes it unopenable. Heavy defeats repair tools. Shred replaces every byte with cryptographic noise while keeping the name and size.
Indistinguishable at rest
The corrupted copy keeps the original filename, the exact byte length and the correct MIME type. It copies, syncs, attaches to email and passes upload forms like any other file. It only fails at the moment something tries to parse it.
Large files and batches
Processing runs in 8 MB slices with a yield to the event loop between them, so a multi-gigabyte video neither freezes the tab nor exhausts memory. Drop in a folder and every file is processed in one pass, at roughly 18 ms per megabyte.
Auditable output
Every run reports the profile used, how many structure markers were destroyed, the percentage of bytes rewritten and a hex view of the header before and after. Optional SHA-256 hashing proves the input and output differ.
Header
Index
Payload
Trailer
Header, index and trailer are gone. Nothing can locate a single entry, so repair has nothing to rebuild from.
What gets destroyed, by format
Corruption is applied to structure first and payload second. This is the landmark each profile targets, and the error the application actually shows afterwards.
%PDF- headerdestroyed
Objects and content streamsentropy
xref tabledestroyed
trailerdestroyed
%%EOFdestroyed
Structure destroyed Entropy scattered
Acrobat: "The file is damaged and could not be repaired."
The reader opens a PDF from the back, so every index at the tail has to go.
| Format | Structure destroyed | What you see |
|---|---|---|
The %PDF- header, every xref table, the trailer and the %%EOF marker | Acrobat: "The file is damaged and could not be repaired" | |
| DOCX, XLSX, PPTX | Local file headers, the central directory and the end-of-central-directory record | Word: "unreadable content", and Open and Repair then fails |
| ZIP, RAR, 7z | The archive index, local headers and RAR recovery records | WinRAR: "Cannot open file as archive" |
| ISO | The full 32 KB system area and the CD001 volume descriptors | Windows: "There was a problem mounting the file" |
| DMG | The koly trailer and the mish block map | macOS: "No mountable file systems" |
| MP4, MOV, MKV | The ftyp brand and the moov atom holding the sample table | VLC: "Your input can't be opened" |
| MP3, WAV, FLAC | ID3 tags, MPEG frame sync words and the FLAC STREAMINFO block | No duration, no artwork, nothing plays |
| JPG, PNG, GIF | SOI, SOF, DHT and SOS markers; the PNG signature, IHDR and IDAT chunks | Broken-image placeholder in every browser |
| PSD, AI | The 8BPS header, 8BIM resource blocks and the embedded PDF xref | Photoshop: "the file is not compatible" |
| EXE, DLL, APK | The MZ stub, the PE header and the section table; the APK signing block | Windows: "not a valid Win32 application" |
Around 87 extensions have a dedicated profile. Anything else falls back to a generic binary profile that overwrites the header and trailer and scatters entropy through the body, so you can corrupt files online here whether or not the format has a page of its own.
Do not take the privacy claim on trust
Every file tool says it does not keep your data. Here that claim is checkable in under a minute, three different ways.
Watch the network tab
Open developer tools, switch to Network, then corrupt a file and sort the requests by size. An upload cannot hide in a list sorted by payload. The only outbound requests belong to the fonts, analytics and advertising tags, and none of them carries your file.
Disconnect and try again
Load this page, turn off Wi-Fi or enable airplane mode, then corrupt a file. It still works, start to finish. A tool that keeps running offline was never sending anything anywhere.
Inspect the code
The corrupter ships unminified with no dependencies. In developer tools, open the Sources panel and read it there: under 500 commented lines, every byte operation visible, and not a single fetch, XHR or WebSocket call anywhere in it.
Your device File read, rewritten and handed back, all in page memory
Any server Never receives the file, because it is never sent
- Requests before
- –
- Requests after
- –
- Sent to this site
- –
Press the button to generate a 256 KB file in memory, corrupt it, and compare the network requests this page has made before and afterwards. Any third-party analytics or advertising request that fires is named in the result; what matters is that nothing is sent back here, because there is no endpoint to send it to.
Who uses a file corrupter, and why
Deliberately broken files are a routine part of building, operating and teaching software.
Developers and QA engineers
Malformed input is one of the most common causes of production incidents and one of the least exercised paths in a codebase. A corrupted file checks that a parser fails closed rather than hanging or allocating unbounded memory, that an upload endpoint returns a useful error, and that file-type validation reads magic bytes instead of trusting the extension.
IT and infrastructure teams
A backup you have never restored is a hypothesis. Corrupt a database dump or a deployment artifact, then run the restore runbook against it and find out whether the integrity check fires, whether the import rolls back cleanly, and whether a bad artifact can overwrite a good one.
Security researchers and forensics
Generate malformed input for a fuzzing corpus, confirm a scanner handles a broken archive without hanging, or produce reproducible damaged evidence files for digital forensics and incident-response training without touching live malware.
Educators and trainers
Show a class what a corrupted file looks like at the byte level, demonstrate why checksums and versioned backups exist, and hand students identical damaged files to practise recovery on. The hex view after each run makes the change visible rather than abstract.
Why malformed input is worth testing on purpose
Storage fails more often, and more quietly, than most teams plan for. In Understanding the Robustness of SSDs under Power Fault (Zheng et al., USENIX FAST 2013), 13 of the 15 solid-state drives tested across five vendors failed when power was cut mid-write. The observed failure modes were not just dead devices: they included bit corruption, shorn writes, unserializable writes and metadata corruption, which is the category that leaves a file present, the correct size, and unreadable.
Mechanical drives are no safer over time. Google's analysis of more than 100,000 disks reported annualised failure rates climbing toward 8.6% by the third year, with latent sector errors accumulating undetected long before a drive is declared dead.
The practical consequence is that the code handling a damaged file will eventually run in production, whether or not anyone has tested it. Corrupting a file deliberately turns that from an incident into a fixture you can run in CI. For a walkthrough of what to check, see testing the error path nobody tests.
How this compares to other online corrupters
The honest version, including where the alternatives are perfectly fine.
| Capability | Files Corrupter | Typical online corrupter |
|---|---|---|
| Where processing happens | Your browser | Uploaded to a server |
| File size limit | None, to a ~2 GB browser ceiling | Often 10 to 100 MB |
| Corruption method | Format-aware, structural | Random byte flips |
| Defeats Office and Acrobat repair | Yes | Frequently not |
| Damage levels | Four | One |
| Batch processing | Yes | One file at a time |
| Keeps name, size and MIME type | Yes | Usually renamed |
| Works offline | Yes | No |
| Reports what it changed | Profile, markers, hex, SHA-256 | Nothing |
| Account required | Never | Sometimes |
What this tool will not do
Worth stating plainly, because a tool that overpromises here wastes your time at the moment it matters most.
- It cannot repair anything. Corruption is one-way. Once the header, index and trailer are gone there is no redundancy left to reconstruct from, by us or by any recovery tool. Keep the original.
- It cannot change a timestamp. Created and modified dates come from your filesystem, not from the file contents. Nothing here can make a file look damaged at a particular moment.
- It cannot defeat a hash recorded earlier. If a system already stored a checksum of the working file, the corrupted copy will not match it. That is the point of checksums.
- It cannot guarantee one specific application. Format profiles target the structures parsers depend on, and the results are consistent, but no tool can promise identical behaviour in every version of every program.
- It never modifies your source file. The file you select is read into memory. The damage is applied to a copy and handed back as a download. The original on disk is untouched.
Read further
The longer explanations behind how these formats fail.
Datamosh, pixel sorting and databending explained Glitch Art File carving: recovering data when the filesystem is gone Forensics Validating file uploads properly Security From a corrupted file to a fuzzing harness Testing Your backup is a hypothesis until you restore it Operations Silent data corruption, and the filesystems that catch it Storage
What each level actually does
Damage is applied to structure first and payload second. That ordering is the difference between "opens with a warning" and "cannot be recovered".
Header and trailer Payload 3.0% of bytes rewritten
Will not open in any normal application.
| Level | Payload rewritten | Structure targeted | Result |
|---|---|---|---|
| Light | ~0.5% | Magic bytes only | Opens with an error or renders partially. Sometimes recoverable. |
| Standard | ~3% | Header, all signatures, trailer | Will not open in any normal application. |
| Heavy | ~12% | Header, all signatures, double trailer | Defeats recovery and repair software entirely. |
| Shred | 100% | Entire file replaced | Every byte becomes cryptographic noise. |
Frequently asked questions
Is Files Corrupter really free?
Yes. Completely free, with no account, no sign-up and no usage limit. The tool runs on your own hardware, so it costs us nothing per file.
Are my files uploaded to a server?
No. Every byte is processed locally in your browser. Nothing is transmitted, logged or stored. Disconnect from the internet and the tool still works.
Can a corrupted file be recovered?
At Standard level and above, no. The engine destroys the structural landmarks recovery tools depend on, so there is nothing left to rebuild from. Always keep an untouched backup.
Does the corrupted file still look normal?
Yes. The output keeps the exact original filename, byte length and MIME type. It only fails when something tries to parse it.
What is the maximum file size?
There is no limit imposed by us. Files are processed in 8 MB slices, so a multi-gigabyte video is handled without exhausting browser memory.
Which file formats are supported?
Any format. Around 87 extensions have a dedicated profile targeting their specific structure, and anything else falls back to a generic binary profile that still breaks the file reliably.