Create a ZIP file

How to Create ZIP

1. 1

   Drop files or a folder

   Up to two thousand files. Dropping a folder keeps its structure; the paths you see are the paths inside the archive.

2. 2

   Name the archive and pick a compression level

   Smart compression is the default: real compression for text and documents, storage for formats that are already compressed.

3. 3

   Create the ZIP and download

   One archive comes back, with the original modification date preserved on every entry.

Why smart compression is the default

Deflate, the algorithm inside every ZIP file, looks for repetition. JPEG, PNG, MP4, MP3 and PDF have already had their repetition squeezed out by their own codecs, so running deflate over them again typically saves well under one percent while costing real seconds of processor time on a large set. Smart mode therefore stores those formats as-is and compresses everything else at level six, which is where the curve of effort against benefit flattens for text, CSV, JSON and Office documents. If you want a uniform rule instead, levels one, six and nine apply to every file without exception, and store mode packs without compressing at all, which is useful when the archive is only a container.

Folder structure and name collisions

Dropping a folder preserves the relative paths, so unzipping recreates the same tree rather than dumping two hundred files into one directory. Flattening is the alternative, and it creates a question the tool has to answer out loud: two files called photo.jpg from different folders cannot both be photo.jpg. Either the second becomes photo-2.jpg, or it is skipped and counted. Both are offered, and neither happens silently. Hidden files, meaning anything with a path segment starting with a dot, are excluded by default because .DS_Store and .git directories are rarely what anyone meant to send.

There is no password option, on purpose

The classic ZIP password uses a stream cipher from 1990 that falls to a known-plaintext attack in seconds on an ordinary laptop; the stronger AES variant is not something the compression library used here can write. Offering the weak one under the word "password" would imply a protection that does not exist, which is worse than offering nothing. If you need to read an encrypted archive rather than create one, the extractor handles both ZipCrypto and AES. If you need to protect what you are sending, the Protect a file tool writes AES-256 archives with a password, which is the strong variant done properly.

Frequently asked questions