How can I set a cookie in a request using Fiddler?

Question

I need to set a cookie before I issue a request to a Web site using Fiddler. How do I do this?

RayLoveless · Accepted Answer · 2013-01-18T17:30:25.277

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Simple...You need to set a header value, with your request, like so:

Cookie: YourCookieName=YourCookieValue

edited Jan 18 '13 at 17:30

answered Oct 05 '12 at 17:00

RayLoveless

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This doesn't set the cookie in a way that the client knows that the cookie is there. The line specified will also effectively "hide" all other cookies. – EricLaw Oct 28 '13 at 23:52
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Just stumbled upon this now as this question is high in Google. For multiple cookies use `Cookie: CookieName1=CookieVal1; CookieName2=CookieVal2` and for path/protocol details use `Cookie: CookieName1=CookieVal1; CookieName2=CookieVal2; path=/; HttpOnly` – EvilDr Aug 13 '14 at 09:04
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If you have multiple cookies from "set-cookie" you must append them all onto one line in the request "cookie" header with "; " delimited. – escape-llc Mar 08 '22 at 17:09

DesLFC · Answer 2 · 2014-01-24T00:55:16.633

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To do this using the FiddlerScript engine, add the following code into the onBeforeRequest method:

oSession.oRequest["Cookie"] = (oSession.oRequest["Cookie"] + ";YourCookieName=YourCookieValue");

This will preserve any other cookies that have been set.

edited Jan 24 '14 at 00:55

answered Jan 24 '14 at 00:20

DesLFC

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I use this one-liner to "replace" the value of a cookie and set the cookie value. It also handles the case where the Cookie header wasn't part of the initial request. `oSession.oRequest['Cookie'] = oSession.oRequest['Cookie'] ? oSession.oRequest['Cookie'].Replace("YourCookieName=","ignoredYourCookieName=") + ";YourCookieName=YourCookieValue" : "YourCookieName=YourCookieValue";` – Tim Lewis Feb 10 '15 at 21:12

score 8 · Answer 3 · answered Jul 27 '10 at 18:47

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You need to be more specific about what you're trying to do.

You can edit (or add) an outbound Cookie header to send a cookie to the website. You can do this either manually or via the FiddlerScript engine. But that doesn't "set" the cookie on the client-- it simply sends it to the server. If you want to set a cookie on the client, you either have to use another means, or you can inject a Set-Cookie response header on a previous response from the server, with the value you want to set on the client.

answered Jul 27 '10 at 18:47

EricLaw

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Thanks Eric, setting the outbound cookie header is precisely what I want to do. (BTW Fiddler is a most excellent tool, I'm working in a team of about 250 developers, each of which use it pretty much every day. We find it just the ticket for diagnosing low-level issues with REST services.) – Jeremy McGee Jul 27 '10 at 19:33

score 5 · Answer 4 · answered Mar 07 '14 at 21:55

You can also use the Fiddler Composer.

Run Fiddler
Open the Composer Tab on the top.

It's easiest if you can start with another request from your web site. To do this capture a the request you want to modify, then drag it from the UI to the composer tab.

A good explanation is here: http://www.debugtheweb.com/Fiddler/help/composer.asp

score 2 · Answer 5 · answered Jul 27 '10 at 09:09

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Fiddler allows your to resend/rebuild an existing request. There is a Request Builder. While rebuilding in the RAW form, modify your cookies.

answered Jul 27 '10 at 09:09

ankitjaininfo

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That's fine for existing requests - but this is a new request that requires a cookie. – Jeremy McGee Jul 27 '10 at 09:13

score 1 · Answer 6 · edited Oct 05 '17 at 12:23

This solution is valid for Cookie based authentication:

If you want to test the API/url which have authentication enabled, please try following, i am showing for MVC web API on IIS server. usually there are more than 1 cookie responsible for authorization, so you may need to send more than 1 cookie in header as follows:

User-Agent: Fiddler Host: localhost:51000 content-Type: application/json Cookie : .ASPXAUTH=xxxxx;ASP.NET_SessionId=yyyy;__RequestVerificationToken=zzzz

score 0 · Answer 7 · answered Oct 05 '17 at 10:48

When running Fiddler as a reverse Proxy you can modify the response headers via FiddlerScript by adding a line in the OnBeforeResponse method:

static function OnBeforeResponse(oSession: Session) {
    // ...
    oSession.oResponse["Set-Cookie"] = "sessionToken=abc123; Expires=Wed, 09 Jun 2021 10:18:14 GMT";
}

Also check Fiddler docs about Modifying a Request or Response for more info.

How can I set a cookie in a request using Fiddler?

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