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Efficiently change file MD5 hashes in bulk to generate brand new hash codes, solving issues like duplicate file checks and upload restrictions.
Modifies the MD5 hash value of a file by appending random data to its end, without affecting the file's normal use (limited to multimedia/archive files, etc.).
Drag files here, or click to upload
Supports videos, images, archives, etc.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
The tool first calculates an MD5 digest for each selected file. When modification runs, it appends one random byte to a copy of the file, then calculates the copy's MD5 and offers the result for download. The original file is not overwritten. The copy keeps the same filename and extension, but its content is one byte longer. This is a byte-level edit, not a checksum repair or a format-aware metadata change.
MD5 is a message-digest algorithm that produces a 128-bit value, commonly written as 32 hexadecimal characters; the algorithm is specified in RFC 1321 (checked 2026-09-29). A changed input generally changes the digest, but MD5 is not encryption and does not prove that a file is unique or trustworthy. IETF RFC 6151 explains collision attacks and advises against MD5 where collision resistance is needed (checked 2026-09-29).
The before-and-after values let you observe that the file bytes changed. They do not show that the modified file remains valid for its format, or that it will pass a signature, checksum, installer, or upload system. A random byte can also repeat on separate runs, so the resulting copy and digest are not guaranteed to differ every time.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Add one or more files. The original MD5 value is calculated and shown in the list.
Choose the batch action and wait for each file status to finish. The action requires the access level indicated by the page.
Review the original and new digests and each file status. Download a result individually, or download a ZIP after all listed files succeed.
Keep the originals in a separate location. Since the copy retains the same name, avoid saving it over the source or mixing the two versions.
Use cases
See how the tool fits into real work and everyday tasks.
Use a disposable sample to compare a file's original and modified digest and explain that a digest is calculated from bytes rather than a filename.
In an isolated test environment, check how a parser handles trailing data. Validate the specific format and preserve a clean source copy; this operation does not repair or repackage the file.
Q&A
Find concise answers to common questions and confusing cases.
That is not guaranteed. The tool appends a byte without updating the file format. Some readers ignore trailing bytes, while strict parsers, signatures, or particular formats may reject the copy.
No. MD5 has known collision weaknesses and is not proof of authenticity. Use a trusted modern digest or digital signature for security-sensitive verification.
The original digest is calculated when a file is added. The modified digest appears only after you start the change and that file finishes successfully.
No. The appended value is one random byte, so it can match a previous run. MD5 also cannot guarantee a unique digest for distinct files.
Notes
Review scope, result limitations, and important precautions before use.
Appending a byte changes the actual file and may break format structures, checksums, signatures, archives, or installers. Use only disposable copies and test them in the intended reader. Do not use this tool to bypass upload restrictions or duplicate-file checks on services; their rules may prohibit altered content. Do not rely on MD5 for passwords, signatures, malware decisions, or trusted integrity verification. Preserve the unmodified file and its trusted source when a file is used for installation, backup, evidence, or delivery.
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