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What file formats of compressed archives does Windows 10 natively know how to work with on fresh install?

There are many file formats for compressed archives. To name a few:

  1. .tar.gz
  2. .zip
  3. .rar
  4. .7z
  5. etc

But I'm especially curious what is the subset of these various "compressed archive" file formats that Microsoft Windows natively knows how to decompress out-of-the-box after a fresh install of the OS -- without having to install additional software.

Which compressed archive file formats does Windows 10 know about on fresh install?

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    Related question here. Answer: Deflate and Deflate64 (this functionality hasn’t been changed since it was introduced). Deflate is the same compression that .zip files support. Background
    – Ramhound
    Commented Sep 20, 2021 at 21:55
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    If you wish to provide compressed files for Windows, you might also ask what versions/types of these archive formats? For example, can MS Windows natively open a pasword-protected Zip, and with what encryption method (e.g., AES-256, ZipCrypto)? It would be nice to have those specifications, though I've not seen such documentation. BTW, include CAB, XPRESnK and LZH as native Windows compressed formats. See docs.microsoft.com/en-us/windows-server/administration/… .
    – DrMoishe Pippik
    Commented Sep 20, 2021 at 22:01
  • The only third party de-compression W10 supports is ZIP, you will have to use 7-zip to do most others.
    – Moab
    Commented Sep 21, 2021 at 0:18
  • “can MS Windows natively open a pasword-protected Zip, and with what encryption method (e.g., AES-256, ZipCrypto)?” - No
    – Ramhound
    Commented Sep 21, 2021 at 0:46

1 Answer 1

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Windows 10 knows only about ZIP archive files; it can create them, and open them. It can't create encrypted ZIP files; it can open them if and only if encrypted using very insecure ZipCrypto encryption (not the default with 3rd-party archivers such as WinRAR and 7-Zip, but can usually be selected as an option). The only way to send a user of native Windows without 3rd-party archiver support an encrypted file is to risk ZipCrypto. (A self-extracting file using any format will work, but email usually objects to executables.) This for Windows 10, last tried in 2021; later versions may extend support.

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  • This claim is wrong. For instance, .cab files are another (obscure) archive format natively supported by Windows. .cab files support DEFALTE and LZX (a variation of the LZ77 family) which should give a bit better compression ratios (source link).
    – Socowi
    Commented Feb 8, 2023 at 13:00
  • Not sure if there are other hidden formats. At least theoretically speaking, Windows supports decompressing gzip and brotli too, because it comes with a pre-installed browser (Edge) which sends the user agent ACCEPT-ENCODING: gzip, deflate, br. Whether or not that functionality is accessible to end users for decompression file archives (e.g. an uncompressed .zip or .cab archive) is another question.
    – Socowi
    Commented Feb 8, 2023 at 15:09
  • Thanks to Socowi for details re my comment. The question I was really answering (not exactly what was asked) was "how can I send an encrypted file to a naïve user of Windows without a 3rd-party archiving program", which I have had to do. My point is that you can do this, but only if you take the steps to use the not very secure ZipCrypto encryption (7-Zip and WinRar both support it, possibly with a different name, and not as default, must select it). This is correct (unless changed in a later Windows) - I did it, a couple of years ago.
    – pol098
    Commented Feb 9, 2023 at 18:02
  • Thanks for clarifying this. OP never mentioned encryption, so I already wondered about that part of your answer.
    – Socowi
    Commented Feb 9, 2023 at 18:22

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