Create a ZIP file

A standard ZIP archive with UTF-8 file names, checked against Info-ZIP (the unzip command); Windows Explorer, macOS Finder, 7-Zip and WinRAR open this same format. Each file is deflated (method 8) when that makes it smaller, otherwise stored (method 0). With a password, each file is written with method 99, WinZip's AES-256 encryption, and the method it was compressed with is named inside the entry (see the password answer). The archive keeps each file's modified date and time in ZIP's own date field, which counts in steps of two seconds (an odd second is rounded down) and holds 1 January 1980 to 31 December 2107: a date before is stored as 1 January 1980, 00:00:00, one after as 31 December 2107, 23:59:58, and the result names each file whose date was moved. A date from 1 January 1970, 00:00:00 UTC, to the end of 1979 is also kept, to the second, in Info-ZIP's extended timestamp field beside it, which 7-Zip and Info-ZIP's unzip read; a program that reads only ZIP's own field shows 1 January 1980. That field counts seconds from 1970 in 32 bits, which Info-ZIP describes as signed, reaching back to 1901, but 7-Zip reads them unsigned and would show a date before 1970 as one after 2038, so such a date is only moved, like a date after 2107, which no 32-bit count from 1970 reaches.

Yes. Press Choose a folder, or drop a folder onto the page in a desktop browser. Files inside keep their relative paths, so sub-folders are preserved in the archive; empty folders are not included. If two entries end up with the same path, the later one gets a number, for example report (2).pdf. When everything you chose is in one folder and you have not typed a name, the ZIP is named after that folder; a name you type is never replaced, and Start again empties it.

The tool builds a classic ZIP, so each file and the whole archive must be under 4 GB and there can be at most 65,535 files. The practical limit is your device's memory, because the archive is assembled in the browser.

Yes. Tick Protect the ZIP with a password and type one of at least 8 characters twice. Each file's contents are then encrypted with AES-256 in the WinZip format (AE-2), each under a key of its own, with a code that lets an unzipper refuse a wrong password and notice a changed file. 7-Zip, WinRAR and Keka open it with the password; Windows' Extract All, macOS Archive Utility and this site's Extract ZIP do not. As in every ZIP, the names of the files and folders, their sizes and their dates stay readable without the password. The format makes each key with only 1,000 rounds of PBKDF2, so a short or common password can be guessed: use a long one. To hide the names as well, make the ZIP with no password, then choose Use in another tool and Encrypt archive (a ZIP up to 64 MB): Encrypt a file makes an .mxenc file with 600,000 rounds, which this site's Decrypt a file opens. The password is never stored, and Start again empties it.

Photos (JPEG, HEIC), videos, MP3s, PDFs with scanned images and Office files are already compressed. For a file larger than 64 KB, the tool first deflates its first 64 KB and stores the file unchanged when that sample does not shrink by at least 2%, so such files cost no extra time. Every other file is deflated whole and stored unchanged only when deflate would not make it smaller, as with a note of a few dozen bytes; an empty file is stored as it is. The result says how many files were stored for each reason. Text, CSV, logs and code usually shrink a lot.

No. The page loads a small script into your browser and every operation runs on your device. You can check this yourself in the browser's network panel: after the page has loaded there are no upload requests. Closing the tab discards the file.

No. These basic tools are free, have no limits set by us and store nothing on our servers. The practical limit is your device's memory for very large files.

Nothing you open or type. While the tab is open, the tool pages keep a short list of the steps taken in it, in the tab's session storage: the step (page opened, started, succeeded, first success, used again or failed), the tool's name, the time, how many files were used and, for a failure, an error code; never a file name, the contents of a file or your text. It holds at most the latest 200 steps, and the browser deletes it when the tab closes. The page never sends it. Where a Report a problem button is shown, you can attach the last 20 steps to your report; nothing is attached unless you tick that box. In local storage the page keeps only choices you made: a Light or Dark theme until you choose System again, the language you picked with the EN / 中文 switch if it differs from your browser's language, and this tool in your recently used list if you switched that list on at the tools page.