COOKIE File

What are COOKIE files and how to open them

Are you having problems opening a COOKIE file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your COOKIE files.

What is a COOKIE file?

A .COOKIE file is a Libwww-perl Cookie_jar file.

Libwww-perl Cookie_jar files store HTTP cookies in a format used by the Perl LWP::UserAgent library. They act as a persistent database of cookies received from web servers so that LWP-based clients can resend those cookies with later requests for access control, session continuity, personalization, and other cookie-based server behaviors.

These files are created by LWP's HTTP::Cookies module (or its subclasses) when configured with the "file" parameter. They are read back by those modules when the client restarts or shares the cookie jar, restoring the state (domains, paths, expiry, secure flag, etc.) of past cookies so the agent behaves as though state was preserved.

The format is text-based and proprietary to LWP. Each cookie is represented in a line beginning "Set-Cookie3", with fields such as DOMAIN, PATH, VERSION, DISCARD, PATH_SPEC alongside the cookie name and value. A header line "#LWP-Cookies-1.0" appears at the top of files created by recent versions. These identifiers distinguish this format from Netscape cookie files or other formats.

How to open COOKIE files

Important: Different programs may use files with the COOKIE file extension for different purposes, so unless you are sure which format your COOKIE file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: September 2, 2026

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