ZIP Password Protector
Add traditional password protection to a .zip archive, compatible with every ZIP tool on the planet.
What is ZIP Password?
A tool that takes an existing ZIP and rewrites it with traditional PKWARE encryption, so opening any entry in the archive requires the password.
How it works
Every entry is decompressed, then re-written with ZipCrypto: a 32-bit key schedule seeded from the password encrypts the data, and a 12-byte header carrying a CRC-derived check byte makes a wrong password detectable. The archive is then rebuilt with the original folder structure and comment.
- Add your files. Drop files (or a whole folder) onto the drop zone. Browsers hand the contents straight to the page, so nothing is uploaded.
- Choose the options. Pick the format, compression, naming rule or split size. Any change re-computes the preview immediately.
- Download the result. Run the tool and grab the archive, the extracted files or the report. Multi-file results come back as a single .zip.
Examples
A 240 MB photo folder → a 52 MB .zip
JPEGs are already compressed, so the archive only saves 10–15% — but adding the folder structure and a manifest makes the upload verifiable.
A download cut off at 1.4 GB
The File Splitter cuts it into 500 MB chunks that fit the host's limit, and the File Joiner reassembles them, refusing any set with a missing part.
A release bundle with checksums
The Manifest Generator writes sha256sum-style lines next to the files, so the recipient can prove the download arrived intact.
Common mistakes
Expecting ZIP to shrink photos, video or audio
Those formats are already compressed; deflate typically saves single digits on them. ZIP is at its best on text, JSON, CSV, logs and source code.
Treating ZipCrypto as real encryption
Traditional ZIP encryption is legacy and breakable. It stops casual snooping only — for secrets, encrypt the contents with AES-256 first.
Renaming extensions to convert a file
Changing .png to .jpg does not change the bytes inside. Some programs will refuse the file, or display garbage. Use a real converter when the format must change.
Splitting without keeping the suffixes
The parts carry .001, .002 … suffixes on purpose: the joiner orders them by number and fails loudly when one is missing, instead of producing a corrupt file.
Frequently asked questions
How strong is this encryption?
Weak by modern standards. ZipCrypto is the original PKZIP cipher: a known-plaintext attack can recover the key, and filenames, sizes and CRC-32 values inside the archive stay readable. It keeps casual eyes out and opens everywhere — treat it as packaging, not cryptography.
What should I use for genuinely secret files?
Encrypt the contents with AES-256 before zipping — the AES Encrypt / Decrypt tool in Security & Crypto does that locally — then put the encrypted files in the archive. Only the password holder can read anything meaningful.
Will Windows Explorer open the result?
Windows' built-in ZIP support refuses encrypted entries, which is a limitation of Explorer rather than the archive. 7-Zip, WinRAR, WinZip, macOS Archive Utility and Info-ZIP all prompt for the password and open it normally.