Cookie file format

Netscape once created a file format for storing cookies on disk so that they would survive browser restarts. curl adopted that file format to allow sharing the cookies with browsers, only to soon watch the browsers move away from that format. Modern browsers no longer use it, while curl still does.

The Netscape cookie file format stores one cookie per physical line in the file with a bunch of associated meta data, each field separated with TAB. That file is called the cookiejar in curl terminology.

When libcurl saves a cookiejar, it creates a file header of its own in which there is a URL mention that links to the web version of this document.

File format

The cookie file format is text based and stores one cookie per line. Lines that start with # are treated as comments.

Each line that specifies a single cookie consists of seven text fields separated with TAB characters (ASCII octet 9). A valid line must end with a newline character.

Fields in the file

Field number, what type and example data and the meaning of it:

  1. string - the domain name
  2. boolean FALSE - include subdomains
  3. string /foobar/ - path
  4. boolean TRUE - send/receive over HTTPS only
  5. number 1462299217 - expires at - seconds since Jan 1st 1970, or 0
  6. string person - name of the cookie
  7. string daniel - value of the cookie