[cookies] Cookies on localhost with explicit domain

I must be missing some basic thing about cookies. On localhost, when I set a cookie on server side and specify the domain explicitly as localhost (or .localhost). the cookie does not seem to be accepted by some browsers.

Firefox 3.5: I checked the HTTP request in Firebug. What I see is:

Set-Cookie:
    name=value;
    domain=localhost;
    expires=Thu, 16-Jul-2009 21:25:05 GMT;
    path=/

or (when I set the domain to .localhost):

Set-Cookie:
    name=value;
    domain=.localhost;
    expires=Thu, 16-Jul-2009 21:25:05 GMT;
    path=/

In either case, the cookie is not stored.

IE8: I did not use any extra tool, but the cookie does not seem to be stored as well, because it’s not being sent back in subsequent requests.

Opera 9.64: Both localhost and .localhost work, but when I check the list of cookies in Preferences, the domain is set to localhost.local even though it’s listed under localhost (in the list grouping).

Safari 4: Both localhost and .localhost work, but they are always listed as .localhost in Preferences. On the other hand, a cookie without an explicit domain, it being shown as just localhost (no dot).

What is the problem with localhost? Because of such a number of inconsistencies, there must be some special rules involving localhost. Also, it’s not completely clear to me why domains must be prefixed by a dot? RFC 2109 explicitly states that:

The value for the Domain attribute contains no embedded dots or does not start with a dot.

Why? The document indicates that it has to do something with security. I have to admit that I have not read the entire specification (may do it later), but it sounds a bit strange. Based on this, setting cookies on localhost would be impossible.

This question is related to cookies setcookie

The answer is


localhost: You can use: domain: ".app.localhost" and it will work. The 'domain' parameter needs 1 or more dots in the domain name for setting cookies. Then you can have sessions working across localhost subdomains such as: api.app.localhost:3000.


Cookie needs to specify SameSite attribute, None value used to be the default, but recent browser versions made Lax the default value to have reasonably robust defense against some classes of cross-site request forgery (CSRF) attacks.

Along with SameSite=Lax you should also have Domain=localhost, so your cookie will be associated to localhost and kept. It should look something like this:

document.cookie = `${name}=${value}${expires}; Path=/; Domain=localhost; SameSite=Lax`;

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie/SameSite


Tried all of the options above. What worked for me was:

  1. Make sure the request to server have withCredentials set to true. XMLHttpRequest from a different domain cannot set cookie values for their own domain unless withCredentials is set to true before making the request.
  2. Do not set Domain
  3. Set Path=/

Resulting Set-Cookie header:

Set-Cookie: session_token=74528588-7c48-4546-a3ae-4326e22449e5; Expires=Sun, 16 Aug 2020 04:40:42 GMT; Path=/

There is an issue on Chromium open since 2011, that if you are explicitly setting the domain as 'localhost', you should set it as false or undefined.


Spent a great deal of time troubleshooting this issue myself.

Using PHP, and Nothing on this page worked for me. I eventually realized in my code that the 'secure' parameter to PHP's session_set_cookie_params() was always being set to TRUE.

Since I wasn't visiting localhost with https my browser would never accept the cookie. So, I modified that portion of my code to conditionally set the 'secure' param based on $_SERVER['HTTP_HOST'] being 'localhost' or not. Working well now.

I hope this helps someone.


When a cookie is set with an explicit domain of 'localhost' as follows...

Set-Cookie: name=value; domain=localhost; expires=Thu, 16-Jul-2009 21:25:05 GMT; path=/

...then browsers ignore it because it does not include at least two periods and is not one of seven specially handled, top level domains.

...domains must have at least two (2) or three (3) periods in them to prevent domains of the form: ".com", ".edu", and "va.us". Any domain that fails within one of the seven special top level domains listed below only require two periods. Any other domain requires at least three. The seven special top level domains are: "COM", "EDU", "NET", "ORG", "GOV", "MIL", and "INT".

Note that the number of periods above probably assumes that a leading period is required. This period is however ignored in modern browsers and it should probably read...

at least one (1) or two (2) periods

Note that the default value for the domain attribute is the host name of the server which generated the cookie response.

So a workaround for cookies not being set for localhost is to simply not specify a domain attribute and let the browser use the default value - this does not appear to have the same constraints that an explicit value in the domain attribute does.


None of the suggested fixes worked for me - setting it to null, false, adding two dots, etc - didn't work.

In the end, I just removed the domain from the cookie if it is localhost and that now works for me in Chrome 38.

Previous code (did not work):

document.cookie = encodeURI(key) + '=' + encodeURI(value) + ';domain=.' + document.domain + ';path=/;';

New code (now working):

 if(document.domain === 'localhost') {
        document.cookie = encodeURI(key) + '=' + encodeURI(value) + ';path=/;' ;
    } else {
        document.cookie = encodeURI(key) + '=' + encodeURI(value) + ';domain=.' + document.domain + ';path=/;';
    }

If you're setting a cookie from another domain (ie you set the cookie by making an XHR cross origin request), then you need to make sure you set the withCredentials attribute to true on the XMLHttpRequest you use to fetch the cookie as described here


There seems to be an issue when you use https://<local-domain> and then http://<local-domain>. The http:// site does not send cookies with requests after https:// site sets them. Force reload and clear cache doesn't help. Only manual clearing of cookies works. Also, if I clear them on the https:// page, then http:// page starts working again.

Looks to be related to "Strict secure cookies". Good explanation here. It was released in Chrome 58 on 2017-04-19.

It looks like Chrome does in fact record both secure cookies and non-secure cookies as it will show the correct cookies depending on the page's protocol when clicking the address bar icon.

But Developer tools > Application > Cookies will not show a non-secure cookie when there is a secure cookie of the same name for the same domain, nor will it send the non-secure cookie with any requests. This seems like a Chrome bug, or if this behavior is expected, there should be some way to view the secure cookies when on a http page and an indication that they are being overridden.

Workaround is to use different named cookies depending on if they are for an http site or https site, and to name them specific to your app. A __Secure- prefix indicates that the cookie should be strictly secure, and is also a good practice because secure and non-secure won't collide. There are other benefits to prefixes too.

Using different /etc/hosts domains for https vs. http access would work too, but one accidental https://localhost visit will prevent any cookies of the same names to work on http://localhost sites - so this is not a good workaround.

I have filed a Chrome bug report.


I was playing around a bit.

Set-Cookie: _xsrf=2|f1313120|17df429d33515874d3e571d1c5ee2677|1485812120; Domain=localhost; Path=/

works in Firefox and Chrome as of today. However, I did not find a way to make it work with curl. I tried Host-Header and --resolve, no luck, any help appreciated.

However, it works in curl, if I set it to

Set-Cookie: _xsrf=2|f1313120|17df429d33515874d3e571d1c5ee2677|1485812120; Domain=127.0.0.1; Path=/

instead. (Which does not work with Firefox.)


Another important detail, the expires= should use the following date time format: Wdy, DD-Mon-YYYY HH:MM:SS GMT (RFC6265 - Section 4.1.1).

Set-Cookie:
  name=value;
  domain=localhost;
  expires=Thu, 16-07-2019 21:25:05 GMT;
  path=/

you can make use of localhost.org or rather .localhost.org it will always resolve to 127.0.0.1


None of the answers here worked for me. I fixed it by putting my PHP as the very very first thing in the page.

Like other headers, cookies must be sent before any output from your script (this is a protocol restriction). This requires that you place calls to this function prior to any output, including and tags as well as any whitespace.

From http://php.net/manual/en/function.setcookie.php


I broadly agree with @Ralph Buchfelder, but here's some amplification of this, by experiment when trying to replicate a system with several subdomains (such as example.com, fr.example.com, de.example.com) on my local machine (OS X / Apache / Chrome|Firefox).

I've edited /etc/hosts to point some imaginary subdomains at 127.0.0.1:

127.0.0.1 localexample.com
127.0.0.1 fr.localexample.com
127.0.0.1 de.localexample.com

If I am working on fr.localexample.com and I leave the domain parameter out, the cookie is stored correctly for fr.localexample.com, but is not visible in the other subdomains.

If I use a domain of ".localexample.com", the cookie is stored correctly for fr.localexample.com, and is visible in other subdomains.

If I use a domain of "localexample.com", or when I was trying a domain of just "localexample" or "localhost", the cookie was not getting stored.

If I use a domain of "fr.localexample.com" or ".fr.localexample.com", the cookie is stored correctly for fr.localexample.com and is (correctly) invisible in other subdomains.

So the requirement that you need at least two dots in the domain appears to be correct, even though I can't see why it should be.

If anyone wants to try this out, here's some useful code:

<html>
<head>
<title>
Testing cookies
</title>
</head>
<body>
<?php
header('HTTP/1.0 200');
$domain = 'fr.localexample.com';    // Change this to the domain you want to test.
if (!empty($_GET['v'])) {
    $val = $_GET['v'];
    print "Setting cookie to $val<br/>";
    setcookie("mycookie", $val, time() + 48 * 3600, '/', $domain);
}
print "<pre>";
print "Cookie:<br/>";
var_dump($_COOKIE);
print "Server:<br/>";
var_dump($_SERVER);
print "</pre>";
?>
</body>
</html>

I had the same issue and I fixed it by putting 2 dots in the cookie name itself without specifying any domain.

set-cookie: name.s1.s2=value; path=/; expires=Sun, 12 Aug 2018 14:28:43 GMT; HttpOnly

document.cookie = valuename + "=" + value + "; " + expires + ";domain=;path=/";

this "domain=;path=/"; will take dynamic domain as its cookie will work in subdomain. if u want to test in localhost it will work


The only thing that worked for me was to set Path=/ on the cookie.

Moreover, the default value of a path attribute seems to be different from browsers to browsers although I tested only two of them (Firefox and Chrome).

Chrome tries to set a cookie as is; if path attribute is omitted in Set-Cookie header then it will not be stored and ignored.

However, Firefox stores a cookie even without an explicit path attribute. It just set it with the requested path; my request url was /api/v1/users and the path was set to /api/v1 automatically.

Anyway, both browsers worked when path was set to / even without an explicit domain, ie Domain=localhost or something. So there are some differences in the way how each browser handles cookies.


I had much better luck testing locally using 127.0.0.1 as the domain. I'm not sure why, but I had mixed results with localhost and .localhost, etc.


After much experimentation and reading various posts, this worked. I could set multiple cookies, read them back and set the time negative and delete them.

func addCookie(w http.ResponseWriter, name string, value string) {
    expire := time.Now().AddDate(0, 0, 1)
    cookie := http.Cookie{
       Name:    name,
       Value:   value,
       Expires: expire,
       Domain:  ".localhost",
       Path:    "/",
    }
    http.SetCookie(w, &cookie)
}

Results I had varied by browser.

Chrome- 127.0.0.1 worked but localhost .localhost and "" did not. Firefox- .localhost worked but localhost, 127.0.0.1, and "" did not.

Have not tested in Opera, IE, or Safari